Salt, acid generator, resist composition and method for producing resist pattern

ABSTRACT

Disclosed are a salt represented by formula (I), an acid generator, and a resist composition including the same:wherein R1, R2 and R3 each represent a hydroxy group, *—O—R10, *—O—CO—O—R10, etc.; L10 represents an alkanediyl group; R10 represents an acid-labile group; R4, R5, R6, R7, R8 and R9 each represent a halogen atom, a haloalkyl group or a hydrocarbon group; A1, A2 and A3 each represent a hydrocarbon group which may have a substituent, and —CH2— included in the hydrocarbon group may be replaced by —O—, —CO—, —S— or —SO2—; m1 represents an integer of 1 to 5, m2, m3, m8 and m9 represent an integer of 0 to 5, m4 to m7 represent an integer of 0 to 4, 1≤m1+m7≤5, 0≤m2+m8≤5, 0≤m3+m9≤5; and AI− represents an organic anion.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a salt, an acid generator, a resistcomposition and a method for producing a resist pattern.

Description of the Related Art

JP 2011-006400 A mentions a salt represented by the following formulaand a resist composition comprising the salt as an acid generator.

JP 2020-015713 A mentions a salt represented by the following formulaand a resist composition comprising the salt as an acid generator.

JP 2020-046661 A mentions salts represented by the following formulasand resist compositions comprising the salts as acid generators,respectively.

SUMMARY OF THE INVENTION

The present invention provides a salt capable of forming a resistpattern with CD Uniformity (CDU) which is better than that of a resistpattern formed from the resist compositions comprising the saltsmentioned above.

The present invention includes the following inventions.

[1] A salt represented by formula (I):

wherein, in formula (I),

-   -   R¹, R² and R³ each independently represent a hydroxy group,        *—O—R¹⁰, *—O—CO—O—R¹⁰ or *—O-L¹⁰-CO—O—R¹⁰, and * represents a        bonding site to the benzene ring,    -   L¹⁰ represents an alkanediyl group having 1 to 6 carbon atoms,    -   R¹⁰ represents an acid-labile group,    -   R⁴, R⁵, R⁶, R⁷, R⁸ and R⁹ each independently represent a halogen        atom, a haloalkyl group having 1 to 12 carbon atoms or a        hydrocarbon group having 1 to 18 carbon atoms, the hydrocarbon        group may have a substituent, and —CH₂— included in the        haloalkyl group and the hydrocarbon group may be replaced by        —O—, —S—, —CO— or —SO₂—,    -   A¹, A² and A³ each independently represent a hydrocarbon group        having 2 to 20 carbon atoms, the hydrocarbon group may have a        substituent, and —CH₂— included in the hydrocarbon group may be        replaced by —O—, —CO—, —S— or —SO₂—,    -   m1 represents an integer of 1 to 5, and when m1 is 2 or more, a        plurality of groups in parentheses may be the same or different        from each other,    -   m2 represents an integer of 0 to 5, and when m2 is 2 or more, a        plurality of groups in parentheses may be the same or different        from each other,    -   m3 represents an integer of 0 to 5, and when m3 is 2 or more, a        plurality of groups in parentheses may be the same or different        from each other,    -   m4 represents an integer of 0 to 4, and when m4 is 2 or more, a        plurality of R⁴ may be the same or different from each other,    -   m5 represents an integer of 0 to 4, and when m5 is 2 or more, a        plurality of R⁵ may be the same or different from each other,    -   m6 represents an integer of 0 to 4, and when m6 is 2 or more, a        plurality of R⁶ may be the same or different from each other,    -   m7 represents an integer of 0 to 4, and when m7 is 2 or more, a        plurality of R⁷ may be the same or different from each other,    -   m8 represents an integer of 0 to 5, and when m8 is 2 or more, a        plurality of R⁸ may be the same or different from each other,    -   m9 represents an integer of 0 to 5, and when m9 is 2 or more, a        plurality of R⁹ may be the same or different from each other,    -   in which 1≤m1+m7≤5, 0≤m2+m8≤5, 0≤m3+m9≤5, and    -   AI⁻ represents an organic anion.        [2] The salt according to [1], wherein A¹ is *—X⁰¹-L⁰¹- or        *-L⁰¹-X⁰¹—, A² is *—X⁰²-L⁰²- or *-L⁰²-X⁰²—, and A³ is *—X⁰³-L⁰³-        or *-L⁰³-X⁰³— (X⁰¹, X⁰² and X⁰³ each independently represent        —O—, —CO—, —S— or —SO₂—, L⁰¹, L⁰² and L⁰³ each independently        represent a hydrocarbon group having 1 to 19 carbon atoms, the        hydrocarbon group may have a substituent, —CH₂— included in the        hydrocarbon group may be replaced by —O—, —CO—, —S— or —SO₂—,        and * represents a bonding site to the benzene ring to which R¹,        R² or R³ is bonded).        [3] The salt according to [2], wherein X⁰¹, X⁰² and X⁰³ are each        independently —O— or —S—.        [4] The salt according to [2] or [3], wherein L⁰¹, L⁰² and L⁰³        are each independently an alkanediyl group having 1 to 6 carbon        atoms (—CH₂— included in the alkanediyl group may be replaced by        —O— or —CO—).        [5] The salt according to any one of [1] to [4], wherein R¹, R²        and R³ are each independently a hydroxy group, *—O—R¹¹ or        *—O-L¹⁰-CO—O—R¹⁰ (* represents a bonding site to the benzene        ring).        [6] The salt according to any one of [1] to [5], wherein the        acid-labile group as for R¹⁰ is a group represented by formula        (1a) or a group represented by formula (2a):

wherein, in formula (1a), R^(aa1), R^(aa2) and R^(aa3) eachindependently represent an alkyl group having 1 to 8 carbon atoms, analkenyl group having 2 to 8 carbon atoms, an alicyclic hydrocarbon grouphaving 3 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to18 carbon atoms, or a group obtained by combining these groups, orR^(aa1) and R^(aa2) may be bonded to each other to form an alicyclichydrocarbon group having 3 to 20 carbon atoms together with carbon atomsto which R^(aa1) and R^(aa2) are bonded, and

-   -   * represents a bonding site:

wherein, in formula (2a), R^(aa1′) and R^(aa2′) each independentlyrepresent a hydrogen atom or a hydrocarbon group having 1 to 12 carbonatoms, R^(aa3′) represents a hydrocarbon group having 1 to 20 carbonatoms, or R^(aa2′) and R^(aa3′) may be bonded to each other to form aheterocyclic group having 3 to 20 carbon atoms together with —C—X^(a)—to which R^(aa2′) and R^(aa3′) are bonded, and —CH₂— included in thehydrocarbon group and the heterocyclic group may be replaced by —O— or—S—,

-   -   X^(a) represents an oxygen atom or a sulfur atom, and    -   * represents a bonding site.        [7] The salt according to any one of [1] to [6], wherein when        m4, m5 or m6 is an integer of 1 or more, R⁴, R⁵ and R⁶ are each        independently a fluorine atom, an iodine atom, a perfluoroalkyl        group having 1 to 4 carbon atoms or an alkyl group having 1 to 4        carbon atoms (—CH₂— included in the alkyl group may be replaced        by —O— or —CO—).        [8] The salt according to any one of [1] to [7], wherein when        m7, m8 or m9 is an integer of 1 or more, R⁷, R⁸ and R⁹ are each        independently a fluorine atom, an iodine atom, a perfluoroalkyl        group having 1 to 4 carbon atoms or an alkyl group having 1 to 4        carbon atoms (—CH₂— included in the alkyl group may be replaced        by —O— or —CO—).        [9] The salt according to any one of [1] to [8], wherein AI⁻ is        a sulfonic acid anion, a sulfonylimide anion, a sulfonylmethide        anion or a carboxylic acid anion.        [10] The salt according to any one of [1] to [9], wherein AI⁻ is        a sulfonic acid anion and the sulfonic acid anion is an anion        represented by formula (I-A):

wherein, in formula (I-A),

-   -   Q¹ and Q² each independently represent a hydrogen atom, a        fluorine atom, an alkyl group having 1 to 6 carbon atoms or a        perfluoroalkyl group having 1 to 6 carbon atoms,    -   L¹ represents a saturated hydrocarbon group having 1 to 24        carbon atoms, —CH₂— included in the saturated hydrocarbon group        may be replaced by —O— or —CO—, and a hydrogen atom included in        the saturated hydrocarbon group may be substituted with a        fluorine atom or a hydroxy group, and    -   Y¹ represents a methyl group which may have a substituent, or an        alicyclic hydrocarbon group having 3 to 24 carbon atoms which        may have a substituent, and —CH₂— included in the alicyclic        hydrocarbon group may be replaced by —O—, —S—, —SO₂— or —CO—.        [11] An acid generator comprising the salt according to any one        of [1] to [10].        [12] A resist composition comprising the acid generator        according to [11] and a resin having an acid-labile group.        [13] The resist composition according to [12], wherein the resin        having an acid-labile group includes at least one selected from        the group consisting of a structural unit represented by formula        (a1-0), a structural unit represented by formula (a1-1) and a        structural unit represented by formula (a1-2):

wherein, in formula (a1-0), formula (a1-1) and formula (a1-2),

-   -   L^(a01), L^(a1) and L^(a2) each independently represent —O— or        *—O—(CH₂)_(k1)—CO—O—, k1 represents an integer of 1 to 7, and *        represents a bonding site to —CO—,    -   R^(a01), R^(a4) and R^(a5) each independently represent a        hydrogen atom, a halogen atom, or an alkyl group having 1 to 6        carbon atoms which may have a halogen atom,    -   R^(a02), R^(a03) and R^(a04) each independently represent an        alkyl group having 1 to 8 carbon atoms, an alicyclic hydrocarbon        group having 3 to 18 carbon atoms, an aromatic hydrocarbon group        having 6 to 18 carbon atoms, or a group obtained by combining        these groups,    -   R^(a6) and R^(a7) each independently represent an alkyl group        having 1 to 8 carbon atoms, an alkenyl group having 2 to 8        carbon atoms, an alicyclic hydrocarbon group having 3 to 18        carbon atoms, an aromatic hydrocarbon group having 6 to 18        carbon atoms, or a group formed by combining these groups,    -   m1 represents an integer of 0 to 14,    -   n1 represents an integer of 0 to 10, and    -   n1′ represents an integer of 0 to 3.        [14] The resist composition according to [12] or [13], wherein        the resin having an acid-labile group includes a structural unit        represented by formula (a2-A):

wherein, in formula (a2-A),

-   -   R^(a50) represents a hydrogen atom, a halogen atom, or an alkyl        group having 1 to 6 carbon atoms which may have a halogen atom,    -   R^(a51) represents a halogen atom, a hydroxy group, an alkyl        group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6        carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms,        an alkoxyalkoxy group having 2 to 12 carbon atoms, an        alkylcarbonyl group having 2 to 4 carbon atoms, an        alkylcarbonyloxy group having 2 to 4 carbon atoms, an        acryloyloxy group or a methacryloyloxy group,    -   A^(a50) represents a single bond or *—X^(a51)-(A^(a52)-X^(a52))        and * represents a bonding site to carbon atoms to which        —R^(a50) is bonded,    -   A^(a52) represents an alkanediyl group having 1 to 6 carbon        atoms,    -   X^(a51) and X^(a52) each independently represent —O—, —CO—O— or        —O—CO—,    -   nb represents 0 or 1, and    -   mb represents an integer of 0 to 4, and when mb is an integer of        2 or more, a plurality of R^(a51) may be the same or different        from each other.        [15] The resist composition according to any one of [12] to        [14], further comprising a salt generating an acid having an        acidity lower than that of an acid generated from the acid        generator.        [16] A method for producing a resist pattern, which comprises:    -   (1) a step of applying the resist composition according to any        one of [12] to [15] on a substrate,    -   (2) a step of drying the applied resist composition to form a        composition layer,    -   (3) a step of exposing the composition layer,    -   (4) a step of heating the exposed composition layer, and    -   (5) a step of developing the heated composition layer.

It is possible to produce a resist pattern with satisfactory CDUniformity (CDU) by using a resist composition comprising a salt of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the present specification, “(meth)acrylic monomer” means “at leastone of acrylic monomer and methacrylic monomer”. Notations such as“(meth)acrylate” and “(meth)acrylic acid” mean the same thing. In groupsmentioned in the present specification, regarding groups capable ofhaving both a linear structure and a branched structure, they may haveeither the linear or branched structure. When —CH₂— included in thehydrocarbon group or the like is replaced by —O—, —S—, —CO— or —SO₂—,the same examples shall apply for each group. “Combined group” means agroup in which two or more exemplified groups are bonded, and valencesof those groups may be appropriately varied by bonding forms. “Derived”or “Induced” means that a polymerizable C═C bond included in themolecule becomes a —C—C— group (single bond) by polymerization. Whenstereoisomers exist, all stereoisomers are included.

[Salt Represented by Formula (I)]

The present invention relates to a salt represented by formula (I)(hereinafter sometimes referred to as “salt (I)”).

Of the salt (I), the side having negative charge is sometimes referredto as “anion (I)”, and the side having positive charge is sometimesreferred to as “cation (I)”:

wherein all symbols are the same as defined above.[Cation (I)]

The cation (I) of the salt represented by formula (I) is a cationrepresented by formula (I-C).

wherein, in formula (I-C), all symbols are the same as defined informula (I).

Examples of the alkanediyl group in L¹⁰ included in R¹, R² and R³ informula (I) include linear alkanediyl groups such as a methylene group,an ethylene group, a propane-1,3-diyl group, a butane-1,4-diyl group, apentane-1,5-diyl group and a hexane-1,6-diyl group; and branchedalkanediyl groups such as an ethane-1,1-diyl group, a propane-1,1-diylgroup, a propane-1,2-diyl group, a propane-2,2-diyl group, apentane-2,4-diyl group, a 2-methylpropane-1,3-diyl group, a2-methylpropane-1,2-diyl group, a pentane-1,4-diyl group and a2-methylbutane-1,4-diyl group.

L¹⁰ is preferably an alkanediyl group having 1 to 3 carbon atoms, andmore preferably a methylene group.

The “acid-labile group” as for R¹⁰ included in R¹, R² and R³ means agroup in which a leaving group including a group represented by R¹⁰ iseliminated by contact with an acid (e.g., trifluoromethanesulfonicacid), thus forming a carboxy group or a hydroxy group.

The acid-labile group is preferably a group represented by formula (1a)(hereinafter sometimes referred to as “acid-labile group (1a)”) or agroup represented by formula (2a) (hereinafter sometimes referred to as“acid-labile group (2a)”):

wherein, in formula (1a), R^(aa1), R^(aa2) and R^(aa3) eachindependently represent an alkyl group having 1 to 8 carbon atoms, analkenyl group having 2 to 8 carbon atoms, an alicyclic hydrocarbon grouphaving 3 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to18 carbon atoms, or a group obtained by combining these groups, orR^(aa1) and R^(aa2) are bonded to each other to form an alicyclichydrocarbon group having 3 to 20 carbon atoms together with carbon atomsto which R^(aa1) and R^(aa2) are bonded, and

* represents a bonding site:

wherein, in formula (2a), R^(aa1′) and R^(aa2′) each independentlyrepresent a hydrogen atom or a hydrocarbon group having 1 to 12 carbonatoms, R^(aa3′) represents a hydrocarbon group having 1 to 20 carbonatoms, or R^(aa2′) and R^(aa3′) are bonded to each other to form aheterocyclic group having 3 to 20 carbon atoms together with —C—X^(a)—to which R^(aa2′) and R^(aa3′) are bonded, and —CH₂— included in thehydrocarbon group and the heterocyclic group may be replaced by —O— or—S—,

-   -   X^(a) represents an oxygen atom or a sulfur atom, and    -   * represents a bonding site.

Examples of the alkyl group as for R^(aa1), R^(aa2) and R^(aa3) includea methyl group, an ethyl group, a propyl group, an n-butyl group, ann-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl groupand the like. The number of carbon atoms of the alkyl group as forR^(aa1), R^(aa2) and R^(aa3) is preferably 1 to 6, and more preferably 1to 4, and still more preferably 1 to 3.

Examples of the alkenyl group as for R^(aa1), R^(aa2) and R^(aa3)include an ethenyl group, a propenyl group, an isopropenyl group, abutenyl group, an isobutenyl group, a tert-butenyl group, a pentenylgroup, a hexenyl group, a heptenyl group, an octenyl group, anisooctenyl group and a nonenyl group.

The alicyclic hydrocarbon group as for R^(aa1), R^(aa2) and R^(aa3) maybe either monocyclic or polycyclic. Examples of the monocyclic alicyclichydrocarbon group include cycloalkyl groups such as a cyclopentyl group,a cyclohexyl group, a cycloheptyl group, a cyclooctyl group and thelike. Examples of the polycyclic alicyclic hydrocarbon group include adecahydronaphthyl group, an adamantyl group, a norbornyl group, and thefollowing groups (* represents a bonding site). The number of carbonatoms of the alicyclic hydrocarbon group as for R^(aa1), R^(aa2) andR^(aa3) is preferably 3 to 16, and more preferably 3 to 12.

Examples of the aromatic hydrocarbon group as for R^(aa1), R^(aa2) andR^(aa3) include aryl groups such as a phenyl group, a naphthyl group, ananthryl group, a biphenyl group and a phenanthryl group. The number ofcarbon atoms of the aromatic hydrocarbon group as for R^(aa1), R^(aa2)and R^(aa3) is preferably 6 to 14, and more preferably 6 to 10.

Examples of the combined group include groups obtained by combining theabove-mentioned alkyl group and alicyclic hydrocarbon group(alkylcycloalkyl groups or cycloalkylalkyl groups, such as amethylcyclohexyl group, a dimethylcyclohexyl group, a methylnorbornylgroup, a cyclohexylmethyl group, an adamantylmethyl group, anadamantyldimethyl group and a norbornylethyl group), aralkyl groups suchas a benzyl group, aromatic hydrocarbon groups having an alkyl group (ap-methylphenyl group, a p-tert-butylphenyl group, a tolyl group, a xylylgroup, a cumenyl group, a mesityl group, a 2,6-diethylphenyl group, a2-methyl-6-ethylphenyl group, etc.), aromatic hydrocarbon groups such asan alicyclic hydrocarbon group (a p-cyclohexylphenyl group, ap-adamantylphenyl group, etc.), aryl-cycloalkyl groups such as aphenylcyclohexyl group, and the like.

When R^(aa1) and R^(aa2) are bonded to each other to form an alicyclichydrocarbon group together with carbon atoms to which R^(aa1) andR^(aa2) are bonded, examples of —C(R^(aa1)) (R^(aa2)) (R^(aa3)) includethe following groups. The alicyclic hydrocarbon group preferably has 3to 16 carbon atoms, and more preferably 3 to 12 carbon atoms. *represents a bonding site to —O—.

Examples of the group represented by formula (1a) include a1,1,1-trialkyl group (a group in which R^(aa1), R^(aa2) and R^(aa3) arean alkyl group, and preferably a tert-butyl group in formula (1a)), a2-alkyladamantan-2-yl group (a group in which R^(aa1), R^(aa2) andcarbon atoms to which R^(aa1) and R^(aa2) are bonded to form anadamantyl group, and R^(aa3) is an alkyl group in formula (1a)) and a1-(adamantan-1-yl)-1,1-dialkyl group (a group in which R^(aa1) andR^(aa2) are an alkyl group and R^(aa3) is an adamantyl group in formula(1a)).

Examples of the hydrocarbon group as for R^(aa1′), R^(aa2′) and R^(aa3′)include an alkyl group, an alicyclic hydrocarbon group, an aromatichydrocarbon group, and groups formed by combining these groups.

Examples of the alkyl group and alicyclic hydrocarbon group includethose which are the same as mentioned in R^(aa1), R^(aa2) and R^(aa3).

Examples of the aromatic hydrocarbon group include aryl groups such as aphenyl group, a naphthyl group, an anthryl group, a biphenyl group and aphenanthryl group.

Examples of the combined group include groups obtained by combining theabove-mentioned alkyl group and alicyclic hydrocarbon group (e.g.,cycloalkylalkyl groups or alkylcycloalkyl groups, such as amethylcyclohexyl group, a dimethylcyclohexyl group, a methylnorbornylgroup, a cyclohexylmethyl group, an adamantylmethyl group, anadamantyldimethyl group and a norbornylethyl group), aralkyl groups suchas a benzyl group, aromatic hydrocarbon groups having an alkyl group (ap-methylphenyl group, a p-tert-butylphenyl group, a tolyl group, a xylylgroup, a cumenyl group, a mesityl group, a 2,6-diethylphenyl group, a2-methyl-6-ethylphenyl group, etc.), aromatic hydrocarbon groups havingan alicyclic hydrocarbon group (a p-cyclohexylphenyl group, ap-adamantylphenyl group, etc.), aryl-cycloalkyl groups such as aphenylcyclohexyl group, and the like.

When R^(aa2′) and R^(aa3′) are bonded to each other to form aheterocyclic group together with carbon atoms and X^(a) to whichR^(aa2′) and R^(aa3′) are bonded, examples of —C(R^(aa1′))(R^(aa2′))—X^(a)—(R^(aa3′)) include the following groups. * represents abonding site.

At least one of R^(aa1′) and R^(aa2′) is preferably a hydrogen atom.

Specific examples of the acid-labile group (1a) include the followinggroups. * represents a bonding site.

Specific examples of the acid-labile group (2a) include the followinggroups. * represents a bonding site.

Each bonding site of R¹, R² and R³ to the benzene ring may be eachindependently the o-position, the m-position or the p-position, withrespect to the bonding site of A¹, A² and A³, respectively.Particularly, R¹, R² and R³ are each independently bonded preferably atthe p-position or the m-position, and more preferably at the p-position,with respect to the bonding site of A¹, A² and A³, respectively.

Preferably, R¹, R² and R³ are each independently a hydroxy group,*—O—R¹⁰ or *—O-L¹⁰-CO—O—R¹⁰, and more preferably *—O—R¹⁰ or*—O-L¹⁰-CO—O—R¹⁰. * represents a bonding site to the benzene ring.

Examples of the halogen atom as for R⁴, R⁵, R⁶, R⁷, R⁸ and R⁹ include afluorine atom, a chlorine atom, a bromine atom and an iodine atom.

The haloalkyl group having 1 to 12 carbon atoms as for R⁴, R⁵, R⁶, R⁷,R⁸ and R⁹ represents an alkyl group having 1 to 12 carbon atoms whichhas a halogen atom, and examples thereof include an alkyl fluoride grouphaving 1 to 12 carbon atoms, an alkyl chloride group having 1 to 12carbon atoms, an alkyl bromide group having 1 to 12 carbon atoms, analkyl iodide group having 1 to 12 carbon atoms and the like. Examples ofthe haloalkyl group include a perfluoroalkyl group having 1 to 12 carbonatoms (a trifluoromethyl group, a pentafluoroethyl group, aheptafluoropropyl group, a nonafluorobutyl group, etc.), a2,2,2-trifluoroethyl group, a 3,3,3-trifluoropropyl group, a4,4,4-trifluorobutyl group, a 3,3,4,4,4-pentafluorobutyl group, achloromethyl group, a bromomethyl group, an iodomethyl group and thelike. The number of carbon atoms of the haloalkyl group is preferably 1to 9, more preferably 1 to 6, still more preferably 1 to 4, and yet morepreferably 1 to 3.

Examples of the hydrocarbon group having 1 to 18 carbon atoms as for R⁴,R⁵, R⁶, R⁷, R⁸ and R⁹ include a chain hydrocarbon group such as an alkylgroup, an alicyclic hydrocarbon group, an aromatic hydrocarbon group,and groups formed by combining these groups.

Examples of the alkyl group include a methyl group, an ethyl group, ann-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group,a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, a2-ethylhexyl group, an octyl group, a nonyl group, a decyl group, anundecyl group and a dodecyl group.

The number of carbon atoms of the chain hydrocarbon group is preferably1 to 12, more preferably 1 to 9, still more preferably 1 to 6, yet morepreferably 1 to 4, and further preferably 1 to 3.

The alicyclic hydrocarbon group may be either monocyclic or polycyclic,and examples thereof include groups shown below. The bonding site can beany position.

Specific examples of the monocyclic alicyclic hydrocarbon group includemonocyclic cycloalkyl groups such as a cyclopropyl group, a cyclobutylgroup, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group and a cyclodecyl group. Examples of the polycyclicalicyclic hydrocarbon group include polycyclic cycloalkyl groups such asa decahydronaphthyl group, an adamantyl group and a norbornyl group. Thenumber of carbon atoms of the alicyclic hydrocarbon group is preferably3 to 18, more preferably 3 to 16, and still more preferably 3 to 12.

Examples of the aromatic hydrocarbon group include a phenyl group, anaphthyl group, a biphenyl group, an anthryl group, a phenanthryl group,a binaphthyl group and the like. The number of carbon atoms of thearomatic hydrocarbon group is preferably 6 to 18, more preferably 6 to14, and still more preferably 6 to 10.

Examples of the group formed by combination include groups formed bycombining an aromatic hydrocarbon group with a chain hydrocarbon group(e.g., an aromatic hydrocarbon group-alkanediyl group-*, an alkylgroup-aromatic hydrocarbon group-*), groups formed by combining analicyclic hydrocarbon group with a chain hydrocarbon group (e.g., analicyclic hydrocarbon group-alkanediyl group-*, an alkyl group-alicyclichydrocarbon group-*) and groups formed by combining an aromatichydrocarbon group with an alicyclic hydrocarbon group (e.g., an aromatichydrocarbon group-alicyclic hydrocarbon group-*, an alicyclichydrocarbon group-aromatic hydrocarbon group-*). * represents a bondingsite.

Examples of the aromatic hydrocarbon group-alkanediyl group-* includearalkyl groups such as a benzyl group and a phenethyl group.

Examples of the alkyl group-aromatic hydrocarbon group-* include a tolylgroup, a xylyl group, a cumenyl group and the like.

Examples of the alicyclic hydrocarbon group-alkanediyl group-* includecycloalkylalkyl groups such as a cyclohexylmethyl group, acyclohexylethyl group, a 1-(adamantan-1-yl)methyl group and a1-(adamantan-1-yl)-1-methylethyl group.

Examples of the alkyl group-alicyclic hydrocarbon group-* includecycloalkyl groups having an alkyl group, such as a methylcyclohexylgroup, a dimethylcyclohexyl group and a 2-alkyladamantan-2-yl group.

Examples of the aromatic hydrocarbon group-alicyclic hydrocarbon group-*include a phenylcyclohexyl group and the like.

Examples of the alicyclic hydrocarbon group-aromatic hydrocarbon group-*include a cyclohexylphenyl group and the like.

In combination, two or more of alicyclic hydrocarbon groups, aromatichydrocarbon groups and chain hydrocarbon groups may be respectivelycombined. Any group may be bonded to the benzene ring.

Examples of the group in which —CH₂— included in the haloalkyl group andthe hydrocarbon group is replaced by —O—, —S—, —CO— or —SO₂— include ahydroxy group (a group in which —CH₂— included in the methyl group isreplaced by —O—), a thiol group (a group in which —CH₂— included in themethyl group is replaced by —S—), a carboxy group (a group in which—CH₂—CH₂— included in the ethyl group is replaced by —O—CO—), an alkoxygroup (a group in which —CH₂— at any position included in the alkylgroup is replaced by —O—), an alkylthio group (a group in which —CH₂— atany position included in the alkyl group is replaced by —S—), analkoxycarbonyl group (a group in which —CH₂—CH₂— at any positionincluded in the alkyl group is replaced by —O—CO—), an alkylcarbonylgroup (a group in which —CH₂— at any position included in the alkylgroup is replaced by —CO—), an alkylsulfonyl group (a group in which—CH₂— at any position included in the alkyl group is replaced by —SO₂—),an alkylcarbonyloxy group (a group in which —CH₂—CH₂— at any positionincluded in the alkyl group is replaced by —CO—O—), an oxy group (agroup in which —CH₂-included in the methylene group is replaced by —O—),a carbonyl group (a group in which —CH₂— included in the methylene groupis replaced by —CO—), a thio group (a group in which —CH₂— included inthe methylene group is replaced by —S—), a sulfonyl group (a group inwhich —CH₂— included in the methylene group is replaced by —SO₂—), analkanediyloxy group (a group in which —CH₂— at any position included inthe alkanediyl group is replaced by —O—), an alkanediyloxycarbonyl group(a group in which —CH₂—CH₂— at any position included in the alkanediylgroup is replaced by —O—CO—), an alkanediylcarbonyl group (a group inwhich —CH₂— at any position included in the alkanediyl group is replacedby —CO—), an alkanediylcarbonyloxy group (a group in which —CH₂—CH₂— atany position included in the alkanediyl group is replaced by —CO—O—), analkanediylthio group (a group in which —CH₂— at any position included inthe alkanediyl group is replaced by —S—), an alkanediylsulfonyl group (agroup in which —CH₂— at any position included in the alkanediyl group isreplaced by —SO₂—), a cycloalkoxy group, a cycloalkylalkoxy group, analkoxycarbonyloxy group, an aromatic hydrocarbon group-carbonyloxygroup, an aromatic hydrocarbon group-carbonyl group, an aromatichydrocarbon group-oxy group, a haloalkoxy group (a group in which —CH₂—at any position included in the haloalkyl group is replaced by —O—), ahaloalkoxycarbonyl group (a group in which —CH₂—CH₂— at any positionincluded in the haloalkyl group is replaced by —O—CO—), ahaloalkylcarbonyl group (a group in which —CH₂— at any position includedin the haloalkyl group is replaced by —CO—), a haloalkylcarbonyloxygroup (a group in which —CH₂—CH₂— at any position included in thehaloalkyl group is replaced by —CO—O—), and a group obtained bycombining two or more of these groups.

Examples of the alkoxy group include alkoxy groups having 1 to 17 carbonatoms, for example, a methoxy group, an ethoxy group, a propoxy group, abutoxy group, a pentyloxy group, a hexyloxy group, an octyloxy group, a2-ethylhexyloxy group, a nonyloxy group, a decyloxy group, an undecyloxygroup and the like. The number of carbon atoms of the alkoxy group ispreferably 1 to 11, more preferably 1 to 6, still more preferably 1 to4, and yet more preferably 1 to 3.

Examples of the alkylthio group include alkylthio groups having 1 to 17carbon atoms, for example, a methylthio group, an ethylthio group, apropylthio group, a butylthio group, a pentylthio group, a hexylthiogroup, an octylthio group, a 2-ethylhexylthio group, a nonylthio group,a decylthio group, an undecylthio group and the like. The number ofcarbon atoms of the alkylthio group is preferably 1 to 11, morepreferably 1 to 6, still more preferably 1 to 4, and yet more preferably1 to 3.

The alkoxycarbonyl group, the alkylcarbonyl group and thealkylcarbonyloxy group represent a group in which a carbonyl group or acarbonyloxy group is bonded to the above-mentioned alkyl group or alkoxygroup.

Examples of the alkoxycarbonyl group include alkoxycarbonyl groupshaving 2 to 17 carbon atoms, for example, a methoxycarbonyl group, anethoxycarbonyl group, a butoxycarbonyl group and the like. Examples ofthe alkylcarbonyl group include alkylcarbonyl groups having 2 to 18carbon atoms, for example, an acetyl group, a propionyl group and abutyryl group. Examples of the alkylcarbonyloxy group includealkylcarbonyloxy groups having 2 to 17 carbon atoms, for example, anacetyloxy group, a propionyloxy group, a butyryloxy group and the like.The number of carbon atoms of the alkoxycarbonyl group is preferably 2to 11, more preferably 2 to 6, still more preferably 2 to 4, and yetmore preferably 2 or 3. The number of carbon atoms of the alkylcarbonylgroup is preferably 2 to 12, more preferably 2 to 6, still morepreferably 2 to 4, and yet more preferably 2 or 3. The number of carbonatoms of the alkylcarbonyloxy group is preferably 2 to 11, morepreferably 2 to 6, still more preferably 2 to 4, and yet more preferably2 or 3.

Examples of the alkylsulfonyl group include alkylsulfonyl groups having1 to 17 carbon atoms, for example, a methylsulfonyl group, anethylsulfonyl group, a propylsulfonyl group, a butylsulfonyl group, apentylsulfonyl group, a hexylsulfonyl group, an octylsulfonyl group, a2-ethylhexylsulfonyl group, a nonylsulfonyl group, a decylsulfonylgroup, an undecylsulfonyl group and the like. The number of carbon atomsof the alkylsulfonyl group is preferably 1 to 11, more preferably 1 to6, still more preferably 1 to 4, and yet more preferably 1 to 3.

Examples of the alkanediyloxy group include alkanediyloxy groups having1 to 17 carbon atoms, for example, a methyleneoxy group, an ethyleneoxygroup, a propanediyloxy group, a butanediyloxy group, a pentanediyloxygroup and the like. The number of carbon atoms of the alkanediyloxygroup is preferably 1 to 11, more preferably 1 to 6, still morepreferably 1 to 4, and yet more preferably 1 to 3.

Examples of the alkanediyloxycarbonyl group includealkanediyloxycarbonyl groups having 2 to 17 carbon atoms, for example, amethyleneoxycarbonyl group, an ethyleneoxycarbonyl group, apropanediyloxycarbonyl group, a butanediyloxycarbonyl group and thelike. Examples of the alkanediylcarbonyl group includealkanediylcarbonyl groups having 2 to 18 carbon atoms, for example, amethylenecarbonyl group, an ethylenecarbonyl group, apropanediylcarbonyl group, a butanediylcarbonyl group, apentanediylcarbonyl group and the like. Examples of thealkanediylcarbonyloxy group include alkanediylcarbonyloxy groups having2 to 17 carbon atoms, for example, a methylenecarbonyloxy group, anethylenecarbonyloxy group, a propanediylcarbonyloxy group, abutanediylcarbonyloxy group and the like. The number of carbon atoms ofthe alkanediyloxycarbonyl group is preferably 2 to 11, more preferably 2to 6, still more preferably 2 to 4, and yet more preferably 2 or 3. Thenumber of carbon atoms of the alkanediylcarbonyl group is preferably 2to 12, more preferably 2 to 6, still more preferably 2 to 4, and yetmore preferably 2 or 3. The number of carbon atoms of thealkanediylcarbonyloxy group is preferably 2 to 11, more preferably 2 to6, still more preferably 2 to 4, and yet more preferably 2 or 3.

Examples of the alkanediylthio group include alkanediylthio groupshaving 1 to 17 carbon atoms, for example, a methylenethio group, anethylenethio group, a propylenethio group and the like. The number ofcarbon atoms of the alkanediylthio group is preferably 1 to 11, morepreferably 1 to 6, still more preferably 1 to 4, and yet more preferably1 to 3.

Examples of the alkanediylsulfonyl group include alkanediylsulfonylgroups having 1 to 17 carbon atoms, for example, a methylenesulfonylgroup, an ethylenesulfonyl group, a propylenesulfonyl group and thelike. The number of carbon atoms of the alkanediylsulfonyl group ispreferably 1 to 11, more preferably 1 to 6, still more preferably 1 to4, and yet more preferably 1 to 3.

Examples of the cycloalkoxy group include cycloalkoxy groups having 3 to17 carbon atoms, for example, a cyclohexyloxy group and the like.Examples of the cycloalkylalkoxy group include cycloalkylalkoxy groupshaving 4 to 17 carbon atoms, for example, a cyclohexylmethoxy group andthe like. Examples of the alkoxycarbonyloxy group includealkoxycarbonyloxy groups having 2 to 16 carbon atoms, for example, abutoxycarbonyloxy group and the like. Examples of the aromatichydrocarbon group-carbonyloxy group include aromatic hydrocarbongroup-carbonyloxy groups having 7 to 17 carbon atoms, for example, abenzoyloxy group and the like. Examples of the aromatic hydrocarbongroup-carbonyl group include aromatic hydrocarbon group-carbonyl groupshaving 7 to 17 carbon atoms, for example, a benzoyl group and the like.Examples of the aromatic hydrocarbon group-oxy group include aromatichydrocarbon group-oxy groups having 6 to 16 carbon atoms, for example, aphenyloxy group and the like.

Examples of the haloalkoxy group, the haloalkoxycarbonyl group, thehaloalkylcarbonyl group and the haloalkylcarbonyloxy group includehaloalkoxy groups having 1 to 11 carbon atoms, haloalkoxycarbonyl groupshaving 2 to 11 carbon atoms, haloalkylcarbonyl groups having 2 to 12carbon atoms and haloalkylcarbonyloxy groups having 2 to 11 carbonatoms, for example, groups in which one or more hydrogen atoms of theabove-mentioned groups are substituted with a halogen atom.

Examples of the group in which —CH₂— included in the alicyclichydrocarbon group is replaced by —O—, —S—, —CO— or —SO₂— include groupsshown below. —O— or —CO— of the groups shown below may be replaced by—S— or —SO₂—. The bonding site can be any position.

When —CH₂— included in the haloalkyl group and the hydrocarbon group isreplaced by —O—, —S—, —CO— or —SO₂—, the number of carbon atoms beforereplacement is taken as the total number of the hydrocarbon group. Thenumber may be 1, or 2 or more.

Examples of the substituent which may be possessed by the hydrocarbongroup as for R⁴, R⁵, R⁶, R⁷, R⁸ and R⁹ include a halogen atom, a cyanogroup and an alkyl group having 1 to 12 carbon atoms (—CH₂— included inthe alkyl group may be replaced by —O— or —CO—).

Examples of the halogen atom include the same groups as mentioned above.

Examples of the alkyl group having 1 to 12 carbon atoms include the samegroups as mentioned above.

When —CH₂— included in the alkyl group as the substituent is replaced by—O— or —CO—, the number of carbon atoms before replacement is taken asthe total number of the alkyl group. Examples of the replaced groupinclude a hydroxy group, a carboxy group, an alkoxy group, analkoxycarbonyl group, an alkylcarbonyl group, an alkylcarbonyloxy groupand the like.

Examples of the alkoxy group, the alkoxycarbonyl group, thealkylcarbonyl group and the alkylcarbonyloxy group include alkoxy groupshaving 1 to 11 carbon atoms, alkoxycarbonyl groups having 2 to 11 carbonatoms, alkylcarbonyl group having 2 to 12 carbon atoms andalkylcarbonyloxy groups having 2 to 11 carbon atoms, for example, thesame groups as mentioned above.

The hydrocarbon group may have one substituent or a plurality ofsubstituents.

Examples of the hydrocarbon group as for A¹, A² and A³ include chainhydrocarbon groups such as an alkanediyl group, alicyclic hydrocarbongroups, aromatic hydrocarbon groups, and groups formed by combiningthese groups. The number of carbon atoms of the hydrocarbon group ispreferably 2 to 19, more preferably 2 to 18, still more preferably 2 to16, yet more preferably 2 to 14, and further preferably 2 to 12.

Examples of the alkanediyl group include linear alkanediyl groups suchas a methylene group, an ethylene group, a propane-1,3-diyl group, abutane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diylgroup, a heptane-1,7-diyl group, an octane-1,8-diyl group, anonane-1,9-diyl group, a decane-1,10-diyl group, an undecane-1,11-diylgroup, a dodecane-1,12-diyl group, a tridecane-1,13-diyl group, atetradecane-1,14-diyl group, a pentadecane-1,15-diyl group, ahexadecane-1,16-diyl group and a heptadecane-1,17-diyl group; and

branched alkanediyl groups such as an ethane-1,1-diyl group, apropane-1,1-diyl group, a propane-1,2-diyl group, a propane-2,2-diylgroup, a pentane-2,4-diyl group, a 2-methylpropane-1,3-diyl group, a2-methylpropane-1,2-diyl group, a pentane-1,4-diyl group and a2-methylbutane-1,4-diyl group.

The number of carbon atoms of the chain hydrocarbon group is preferably2 to 18, more preferably 2 to 12, still more preferably 2 to 9, yet morepreferably 2 to 6, further preferably 2 to 4, and still furtherpreferably 2 or 3.

The alicyclic hydrocarbon group may be either monocyclic or polycyclic,and examples thereof include groups show below. The bonding site can beany position.

Specific examples thereof include monocyclic alicyclic hydrocarbongroups which are monocyclic cycloalkanediyl groups, such as acyclobutane-1,3-diyl group, a cyclopentane-1,3-diyl group, acyclohexane-1,4-diyl group and a cyclooctane-1,5-diyl group; and

polycyclic alicyclic hydrocarbon groups which are polycycliccycloalkanediyl groups, such as a norbornane-1,4-diyl group, anorbornane-2,5-diyl group, an adamantane-1,5-diyl group and anadamantane-2,6-diyl group.

The number of carbon atoms of the alicyclic hydrocarbon group ispreferably 3 to 18, more preferably 3 to 16, still more preferably 3 to12, and yet more preferably 3 to 10.

Examples of the aromatic hydrocarbon group include aromatic hydrocarbongroups, for example, arylene groups such as a phenylene group, anaphthylene group, an anthrylene group, a biphenylene group and aphenanthrylene group. The number of carbon atoms of the aromatichydrocarbon group is preferably 6 to 18, more preferably 6 to 14, andstill more preferably 6 to 10.

Examples of the group formed by combination include groups formed bycombining an alicyclic hydrocarbon group with an alkanediyl group,groups formed by combining an aromatic hydrocarbon group with analkanediyl group, and groups formed by combining an alicyclichydrocarbon group with an aromatic hydrocarbon group. Here, thealkanediyl group in the combination with the alicyclic hydrocarbon groupand/or the aromatic hydrocarbon group may include a methylene group. Incombination, two or more of chain hydrocarbon groups, alicyclichydrocarbon groups and aromatic hydrocarbon groups may be respectivelycombined. Any group may be bonded to the benzene ring to which R¹, R² orR³ is bonded.

Examples of the group formed by combining an alicyclic hydrocarbon groupwith an alkanediyl group include a -divalent alicyclic hydrocarbongroup-alkanediyl group-, an -alkanediyl group-divalent alicyclichydrocarbon group-alkanediyl group-, an -alkanediyl group-divalentalicyclic hydrocarbon group- and the like.

Examples of the group formed by combining an aromatic hydrocarbon groupwith an alkanediyl group include a -divalent aromatic hydrocarbongroup-alkanediyl group-, an -alkanediyl group-divalent aromatichydrocarbon group-alkanediyl group-, an -alkanediyl group-divalentaromatic hydrocarbon group- and the like.

Examples of the group formed by combining an alicyclic hydrocarbon groupwith an aromatic hydrocarbon group include an -aromatic hydrocarbongroup-alicyclic hydrocarbon group-, an -alicyclic hydrocarbongroup-aromatic hydrocarbon group-, an -alicyclic hydrocarbongroup-aromatic hydrocarbon group-an alicyclic hydrocarbon group- and thelike.

When —CH₂— included in the hydrocarbon group is replaced by —O—, —CO—,—S— or —SO₂—, the number of carbon atoms before replacement is taken asthe total number of the hydrocarbon group. The number may be either 1,or 2 or more.

Examples of the group in which —CH₂— included in the hydrocarbon groupis replaced by —O—, —CO—, —S— or —SO₂— include a hydroxy group (a groupin which —CH₂— included in the methyl group is replaced by —O—), acarboxy group (a group in which —CH₂—CH₂— included in the ethyl group isreplaced by —O—CO—), a thiol group (a group in which —CH₂-included inthe methyl group is replaced by —S—), an alkoxy group (a group in which—CH₂— at any position included in the alkyl group is replaced by —O—),an alkoxycarbonyl group (a group in which —CH₂—CH₂— at any positionincluded in the alkyl group is replaced by —O—CO—), an alkylcarbonylgroup (a group in which —CH₂— at any position included in the alkylgroup is replaced by —CO—), an alkylcarbonyloxy group (a group in which—CH₂—CH₂— at any position included in the alkyl group is replaced by—CO—O—), an alkylthio group (a group in which —CH₂— at any positionincluded in the alkyl group is replaced by —S—), an alkylsulfonyl group(a group in which —CH₂— at any position included in the alkyl group isreplaced by —SO₂—), an oxy group (a group in which —CH₂— included in themethylene group is replaced by —O—), a carbonyl group (a group in which—CH₂— included in the methylene group is replaced by —CO—), a thio group(a group in which —CH₂— included in the methylene group is replaced by—S—), a sulfonyl group (a group in which —CH₂— included in the methylenegroup is replaced by —SO₂—), an alkanediyloxy group (a group in which—CH₂— at any position included in the alkanediyl group is replaced by—O—), an alkanediyloxycarbonyl group (a group in which —CH₂—CH₂— at anyposition included in the alkanediyl group is replaced by —O—CO—), analkanediylcarbonyl group (a group in which —CH₂— at any positionincluded in the alkanediyl group is replaced by —CO—), analkanediylcarbonyloxy group (a group in which —CH₂—CH₂— at any positionincluded in the alkanediyl group is replaced by —CO—O—), analkanediylsulfonyl group (a group in which —CH₂— at any positionincluded in the alkanediyl group is replaced by —SO₂—), analkanediylthio group (a group in which —CH₂— at any position included inthe alkanediyl group is replaced by —S—), a cycloalkoxy group, acycloalkylalkoxy group, an alkoxycarbonyloxy group, an aromatichydrocarbon group-carbonyloxy group, an aromatic hydrocarbongroup-carbonyl group, an aromatic hydrocarbon group-oxy group, a groupobtained by combining two or more groups of these groups, and the like.

Examples of the alkoxy group include alkoxy groups having 1 to 17 carbonatoms, for example, a methoxy group, an ethoxy group, a propoxy group, abutoxy group, a pentyloxy group, a hexyloxy group, an octyloxy group, a2-ethylhexyloxy group, a nonyloxy group, a decyloxy group, an undecyloxygroup and the like. The number of carbon atoms of the alkoxy group ispreferably 1 to 11, more preferably 1 to 6, still more preferably 1 to4, and yet more preferably 1 to 3.

The alkoxycarbonyl group, the alkylcarbonyl group and thealkylcarbonyloxy group represent a group in which a carbonyl group or acarbonyloxy group is bonded to the above-mentioned alkyl group or alkoxygroup.

Examples of the alkoxycarbonyl group include alkoxycarbonyl groupshaving 2 to 17 carbon atoms, for example, a methoxycarbonyl group, anethoxycarbonyl group, a butoxycarbonyl group and the like. Examples ofthe alkylcarbonyl group include alkylcarbonyl groups having 2 to 18carbon atoms, for example, an acetyl group, a propionyl group and abutyryl group. Examples of the alkylcarbonyloxy group includealkylcarbonyloxy groups having 2 to 17 carbon atoms, for example, anacetyloxy group, a propionyloxy group, a butyryloxy group and the like.The number of carbon atoms of the alkoxycarbonyl group is preferably 2to 11, more preferably 2 to 6, still more preferably 2 to 4, and yetmore preferably 2 or 3. The number of carbon atoms of the alkylcarbonylgroup is preferably 2 to 12, more preferably 2 to 6, still morepreferably 2 to 4, and yet more preferably 2 or 3. The number of carbonatoms of the alkylcarbonyloxy group is preferably 2 to 11, morepreferably 2 to 6, still more preferably 2 to 4, and yet more preferably2 or 3.

Examples of the alkylthio group include alkylthio groups having 1 to 17carbon atoms, for example, a methylthio group, an ethylthio group, apropylthio group, a butylthio group, a pentylthio group, a hexylthiogroup, an octylthio group, a 2-ethylhexylthio group, a nonylthio group,a decylthio group, an undecylthio group and the like. The number ofcarbon atoms of the alkylthio group is preferably 1 to 11, morepreferably 1 to 6, still more preferably 1 to 4, and yet more preferably1 to 3.

Examples of the alkylsulfonyl group include alkylsulfonyl groups having1 to 17 carbon atoms, for example, a methylsulfonyl group, anethylsulfonyl group, a propylsulfonyl group, a butylsulfonyl group, apentylsulfonyl group, a hexylsulfonyl group, an octylsulfonyl group, a2-ethylhexylsulfonyl group, a nonylsulfonyl group, a decylsulfonylgroup, an undecylsulfonyl group and the like. The number of carbon atomsof the alkylsulfonyl group is preferably 1 to 11, more preferably 1 to6, still more preferably 1 to 4, and yet more preferably 1 to 3.

Examples of the alkanediyloxy group include alkanediyloxy group having 1to 17 carbon atoms, for example, a methyleneoxy group, an ethyleneoxygroup, a propanediyloxy group, a butanediyloxy group, a pentanediyloxygroup and the like. The number of carbon atoms of the alkanediyloxygroup is preferably 1 to 11, more preferably 1 to 6, still morepreferably 1 to 4, and yet more preferably 1 to 3.

Examples of the alkanediyloxycarbonyl group includealkanediyloxycarbonyl groups having 2 to 17 carbon atoms, for example, amethyleneoxycarbonyl group, an ethyleneoxycarbonyl group, apropanediyloxycarbonyl group, a butanediyloxycarbonyl group and thelike. Examples of the alkanediylcarbonyl group includealkanediylcarbonyl groups having 2 to 18 carbon atoms, for example, amethylenecarbonyl group, an ethylenecarbonyl group, apropanediylcarbonyl group, a butanediylcarbonyl group, apentanediylcarbonyl group and the like. Examples of thealkanediylcarbonyloxy group include alkanediylcarbonyloxy groups having2 to 17 carbon atoms, for example, a methylenecarbonyloxy group, anethylenecarbonyloxy group, a propanediylcarbonyloxy group, abutanediylcarbonyloxy group and the like. The number of carbon atoms ofthe alkanediyloxycarbonyl group is preferably 2 to 11, more preferably 2to 6, still more preferably 2 to 4, and yet more preferably 2 or 3. Thenumber of carbon atoms of the alkanediylcarbonyl group is preferably 2to 12, more preferably 2 to 6, still more preferably 2 to 4, and yetmore preferably 2 or 3. The number of carbon atoms of thealkanediylcarbonyloxy group is preferably 2 to 11, more preferably 2 to6, still more preferably 2 to 4, and yet more preferably 2 or 3.

Examples of the alkanediylsulfonyl group include alkanediylsulfonylgroups having 1 to 17 carbon atoms, for example, a methylenesulfonylgroup, an ethylenesulfonyl group, a propylenesulfonyl group and thelike. The number of carbon atoms of the alkanediylsulfonyl group ispreferably 1 to 11, more preferably 1 to 6, still more preferably 1 to4, and yet more preferably 1 to 3.

Examples of the alkanediylthio group include alkanediylthio groupshaving 1 to 17 carbon atoms, for example, a methylenethio group, anethylenethio group, a propylenethio group and the like. The number ofcarbon atoms of the alkanediylthio group is preferably 1 to 11, morepreferably 1 to 6, still more preferably 1 to 4, and yet more preferably1 to 3.

Examples of the cycloalkoxy group include cycloalkoxy groups having 3 to17 carbon atoms, for example, a cyclohexyloxy group and the like.Examples of the cycloalkylalkoxy group include cycloalkylalkoxy groupshaving 4 to 17 carbon atoms, for example, a cyclohexylmethoxy group andthe like. Examples of the alkoxycarbonyloxy group includealkoxycarbonyloxy groups having 2 to 16 carbon atoms, for example, abutoxycarbonyloxy group and the like. Examples of the aromatichydrocarbon group-carbonyloxy group include aromatic hydrocarbongroup-carbonyloxy groups having 7 to 17 carbon atoms, for example, abenzoyloxy group and the like. Examples of the aromatic hydrocarbongroup-carbonyl group include aromatic hydrocarbon group-carbonyl groupshaving 7 to 17 carbon atoms, for example, a benzoyl group and the like.Examples of the aromatic hydrocarbon group-oxy group include aromatichydrocarbon group-oxy groups having 6 to 16 carbon atoms, for example, aphenyloxy group and the like.

Examples of the group in which —CH₂— included in the alicyclichydrocarbon group is replaced by —O—, —CO—, —S— or —SO₂— include groupsshown below. —O— or —CO— of the groups shown below may be replaced by—S— or —SO₂—. The bonding site can be any position.

Examples of the substituent which may be possessed by the hydrocarbongroup as for A¹, A² and A³ include the same groups as mentioned for R⁴to R⁹.

It is preferable that A¹, A² and A³ are each independently a hydrocarbongroup having 2 to 20 carbon atoms (the hydrocarbon group may have asubstituent, —CH₂— included in the hydrocarbon group may be replaced by—O—, —CO—, —S— or —SO₂—, in which at least one of —CH₂— included in thehydrocarbon group is replaced by —O—, —CO—, —S— or —SO₂—). Specifically,it is more preferable that A¹ is *-L⁰¹¹-X⁰¹-L⁰¹²-, A² is*-L⁰²¹-X⁰²-L⁰²²-, and A³ is *-L⁰³¹-X⁰³-L⁰³²-(X⁰¹, X⁰² and X⁰³ eachindependently represent —O—, —CO—, —S— or —SO₂—, L⁰¹¹, L⁰¹², L⁰²¹, L⁰²²,L⁰³1 and L⁰³² each independently represent a single bond or ahydrocarbon group having 1 to 19 carbon atoms, the hydrocarbon group mayhave a substituent, —CH₂— included in the hydrocarbon group may bereplaced by —O—, —CO—, —S— or —SO₂—, in which the total number of carbonatoms of L⁰¹¹ and L⁰¹² is 1 to 19, the total number of carbon atoms ofL⁰²¹ and L⁰²² is 1 to 19, the total number of carbon atoms of L⁰³¹ andL⁰³² is 1 to 19, and * represents a bonding site to the benzene ring towhich R¹, R² or R³ is bonded), and it is still more preferable that A¹is *—X⁰¹-L⁰¹- or *-L⁰¹-X⁰¹—, A² is *—X⁰²-L⁰²- or *-L⁰²-X⁰²—, and A³ is*—X⁰³-L⁰³ or *-L⁰³-X⁰³ (X⁰¹, X⁰² and X⁰³ each independently represent—O—, —CO—, —S— or —SO₂—, L⁰¹, L⁰² and L⁰³ each independently represent ahydrocarbon group having 1 to 19 carbon atoms, the hydrocarbon group mayhave a substituent, —CH₂— included in the hydrocarbon group may bereplaced by —O—, —CO—, —S— or —SO₂—, and * represents a bonding site tothe benzene ring to which R¹, R² or R³ is bonded).

Examples of the hydrocarbon group having 1 to 19 carbon atoms as forL⁰¹¹, L⁰¹², L⁰²¹, L⁰²², L⁰³¹, L⁰³², L⁰¹, L⁰² and L⁰³ (the hydrocarbongroup may have a substituent, and —CH₂— included in the hydrocarbongroup may be replaced by —O—, —CO—, —S— or —SO₂—) include the samegroups as mentioned for A¹, A² and A³ in the range of 1 to 19 carbonatoms.

Preferably, X⁰¹, X⁰² and X⁰³ are each independently —O— or —S—, and morepreferably —O—.

Preferably, L⁰¹¹, L⁰¹², L⁰²¹, L⁰²², L⁰³1 and L⁰³² are each independentlya single bond or a hydrocarbon group having 1 to 18 carbon atoms (—CH₂—included in the hydrocarbon group may be replaced by —O—, —CO—, —S— or—SO₂—), more preferably a single bond or a hydrocarbon group having 1 to14 carbon atoms (—CH₂— included in the hydrocarbon group may be replacedby —O—, —CO—, —S— or —SO₂—), still more preferably a single bond, achain hydrocarbon group having 1 to 9 carbon atoms, an alicyclichydrocarbon group having 3 to 12 carbon atoms, or a group obtained bycombining a chain hydrocarbon group having 1 to 4 carbon atoms with analicyclic hydrocarbon group having 3 to 10 carbon atoms (—CH₂— includedin the chain hydrocarbon group and the alicyclic hydrocarbon group maybe replaced by —O—, —CO—, —S— or —SO₂—), yet more preferably a singlebond or an alkanediyl group having 1 to 6 carbon atoms (—CH₂-included inthe alkanediyl group may be replaced by —O— or —CO—), further preferablya single bond or an alkanediyl group having 1 to 4 carbon atoms (—CH₂—included in the alkanediyl group may be replaced by —O— or —CO—), andstill further preferably a single bond or an alkanediyl group having 1to 3 carbon atoms (—CH₂— included in the alkanediyl group may bereplaced by —O— or —CO—). Of these, a single bond, a methylene group, anethane-1,1-diyl group, a propane-1,1-diyl group, a propane-2,2-diylgroup, a carbonyl group, a carbonyloxy group, a carbonyloxymethylenegroup, an ethyleneoxy group, a methylenecarbonyloxymethylene group or anethyleneoxycarbonyl group is preferable, and a single bond or amethylene group is more preferable. In which, the total number of carbonatoms of L⁰¹1 and L⁰¹² is 1 to 19, the total number of carbon atoms ofL⁰21 and L⁰²² is 1 to 19, and the total number of carbon atoms of L⁰³1and L⁰³² is 1 to 19.

Preferably, L⁰¹, L⁰² and L⁰³ are each independently a hydrocarbon grouphaving 1 to 18 carbon atoms (—CH₂— included in the hydrocarbon group maybe replaced by —O—, —CO—, —S— or —SO₂—), more preferably a hydrocarbongroup having 1 to 14 carbon atoms (—CH₂— included in the hydrocarbongroup may be replaced by —O—, —CO—, —S— or —SO₂—), still more preferablya chain hydrocarbon group having 1 to 9 carbon atoms, an alicyclichydrocarbon group having 3 to 12 carbon atoms, or a group obtained bycombining a chain hydrocarbon group having 1 to 4 carbon atoms with analicyclic hydrocarbon group having 3 to 10 carbon atoms (—CH₂— includedin the chain hydrocarbon group and the alicyclic hydrocarbon group maybe replaced by —O—, —CO—, —S— or —SO₂—), yet more preferably analkanediyl group having 1 to 6 carbon atoms (—CH₂— included in thealkanediyl group may be replaced by —O— or —CO—), further preferably analkanediyl group having 1 to 4 carbon atoms (—CH₂— included in thealkanediyl group may be replaced by —O— or —CO—), and still furtherpreferably an alkanediyl group having 1 to 3 carbon atoms (—CH₂—included in the alkanediyl group may be replaced by —O— or —CO—). Ofthese, a methylene group, an ethane-1,1-diyl group, a propane-1,1-diylgroup, a propane-2,2-diyl group, a carbonyl group, a carbonyloxy group,a carbonyloxymethylene group, an ethyleneoxy group, amethylenecarbonyloxymethylene group or an ethyleneoxycarbonyl group ispreferable, and a methylene group is more preferable.

The bonding site of A¹, A² and A³ to the benzene ring to which S⁺ isbonded may be each independently the o-position, the m-position or thep-position, with respect to the bonding site of S+, respectively.Particularly, when m1, m2 and m3 are 1, A¹, A² and A³ are eachindependently bonded preferably at the p-position or the m-position, andmore preferably at the p-position, with respect to the bonding site ofS+, respectively. When m1, m2 and m3 are 2, it is preferable that one ofA¹, one of A² and one of A³ are each independently bonded at theo-position or the m-position and one of A¹, one of A² and one of A³ areeach independently bonded at the o-position or the m-position, and it ismore preferable that two of A¹, two of A² and two of A³ are eachindependently bonded at the m-position, with respect to the bonding siteof S+, respectively. When m1, m2 and m3 are 3, it is preferable that twoof A¹, two of A² and two of A³ are each independently bonded at theo-position or the m-position and one of A¹, one of A² and one of A³ areeach independently bonded at the p-position or the m-position, and it ismore preferable that two of A¹, two of A² and two of A³ are eachindependently bonded at the m-position and one of A¹, one of A² and oneof A³ are each independently bonded at the p-position, with respect tothe bonding site of S+, respectively. When m1, m2 and m3 are 4, it ispreferable that two of A¹, two of A² and two of A³ are eachindependently bonded at the o-position or the m-position and two of A¹,two of A² and two of A³ are each independently bonded at the p-positionor the m-position, and it is more preferable that two of A¹, two of A²and two of A³ are each independently bonded at the o-position and two ofA¹, two of A² and two of A³ are each independently bonded at them-position, with respect to the bonding site of S+, respectively.

m1 is preferably 1, 2, 3 or 4, more preferably 1, 2 or 3, still morepreferably 1 or 2, and yet more preferably 1.

m2 is preferably 0, 1, 2, 3 or 4, more preferably 0, 1, 2 or 3, stillmore preferably 0, 1 or 2, and yet more preferably 0 or 1.

m3 is preferably 0, 1, 2, 3 or 4, more preferably 0, 1, 2 or 3, stillmore preferably 0, 1 or 2, and yet more preferably 0 or 1.

m4 is preferably 0, 1, 2 or 4, and more preferably 0, 1 or 2.

m5 is preferably 0, 1, 2 or 4, and more preferably 0, 1 or 2.

m6 is preferably 0, 1, 2 or 4, and more preferably 0, 1 or 2.

m7 is preferably 0, 1, 2 or 3, more preferably 0, 1 or 2, and still morepreferably 0 or 1.

m8 is preferably 0, 1, 2 or 3, more preferably 0, 1 or 2, and still morepreferably 0 or 1.

m9 is preferably 0, 1, 2 or 3, more preferably 0, 1 or 2, and still morepreferably 0 or 1.

Particularly, at least one of m8 and m9 is preferably an integer of 1 ormore.

Preferably, R⁴, R⁵ and R⁶ are each independently a halogen atom, analkyl fluoride group having 1 to 6 carbon atoms or an alkyl group having1 to 6 carbon atoms (—CH₂-included in the alkyl group may be replaced by—O— or —CO—), more preferably a halogen atom, an alkyl fluoride grouphaving 1 to 4 carbon atoms or an alkyl group having 1 to 4 carbon atoms(—CH₂— included in the alkyl group may be replaced by —O— or —CO—),still more preferably a fluorine atom, an iodine atom, a perfluoroalkylgroup having 1 to 4 carbon atoms or an alkyl group having 1 to 4 carbonatoms (—CH₂— included in the alkyl group may be replaced by —O— or—CO—), and yet more preferably a fluorine atom, an iodine atom, ahydroxy group, a methoxy group or a trifluoromethyl group.

The bonding site of R⁴, R⁵ and R⁶ to the benzene ring may be eachindependently the o-position, the m-position or the p-position, withrespect to the bonding site of A¹, A² and A³, respectively.Particularly, when m4, m5 and m6 are 1, R⁴, R⁵ and R⁶ are eachindependently bonded preferably at the p-position or the m-position, andmore preferably at the m-position, with respect to the bonding site ofA¹, A² and A³, respectively. When m4, m5 and m6 are 2, it is preferablethat one of R⁴, one of R⁵ and one of R⁶ are each independently bonded atthe o-position or the m-position and one of R⁴, one of R⁵ and one of R⁶are each independently bonded at the p-position or the m-position, andit is more preferable that two of R⁴, two of R⁵ and two of R⁶ are eachindependently bonded at the m-position, with respect to the bonding siteof A¹, A² and A³, respectively. When m4, m5 and m6 are 3, it ispreferable that two of R⁴, two of R⁵ and two of R⁶ are eachindependently bonded at the o-position or the m-position and one of R⁴,one of R⁵ and one of R⁶ are each independently bonded at the p-positionor the m-position, and it is more preferable that one of R⁴, one of R⁵and one of R⁶ are each independently bonded at the o-position and two ofR⁴, two of R⁵ and two of R⁶ are each independently bonded at them-position, with respect to the bonding site of A¹, A² and A³,respectively. When m4, m5 and m6 are 4, it is preferable that two of R⁴,two of R⁵ and two of R⁶ are each independently bonded at the o-positionor the m-position and two of R⁴, two of R⁵ and two of R⁶ are eachindependently bonded at the p-position or the m-position, and it is morepreferable that two of R⁴, two of R⁵ and two of R⁶ are eachindependently bonded at the o-position and two of R⁴, two of R⁵ and twoof R⁶ are each independently bonded at the m-position, with respect tothe bonding site of A¹, A² and A³, respectively.

Preferably, R⁷, R⁸ and R⁹ are each independently a halogen atom, analkyl fluoride group having 1 to 6 carbon atoms or an alkyl group having1 to 6 carbon atoms (—CH₂-included in the alkyl group may be replaced by—O— or —CO—), more preferably a halogen atom, an alkyl fluoride grouphaving 1 to 4 carbon atoms or an alkyl group having 1 to 4 carbon atoms(—CH₂— included in the alkyl group may be replaced by —O— or —CO—),still more preferably a fluorine atom, an iodine atom, a perfluoroalkylgroup having 1 to 4 carbon atoms or an alkyl group having 1 to 4 carbonatoms (—CH₂— included in the alkyl group may be replaced by —O— or—CO—), and yet more preferably a fluorine atom, an iodine atom, atrifluoromethyl group, a hydroxy group, a methoxy group, a methyl groupor a t-butyl group.

The bonding site of R⁷, R⁸ and R⁹ to the benzene ring may be eachindependently the o-position, the m-position or the p-position withrespect to the bonding site of S+, respectively. Particularly, when m7,m8 and m9 are 1, R⁷, R⁸ and R⁹ are each independently bonded preferablyat the p-position or the m-position, and more preferably at thep-position, with respect to the bonding site of S⁺, respectively. Whenm7, m8 and m9 are 2, it is preferable that one of R⁷, one of R⁸ and oneof R⁹ are each independently bonded at the o-position or the m-positionand one of R⁷, one of R⁸ and one of R⁹ are each independently bonded atthe p-position or the m-position, and it is more preferable that one ofR⁷, one of R⁸ and one of R⁹ are each independently bonded at them-position and one of R⁷, one of R⁸ and one of R⁹ are each independentlybonded at the p-position or the m-position, with respect to the bondingsite of S⁺, respectively. When m7, m8 and m9 are 3, it is preferablethat two of R⁷, two of R⁸ and two of R⁹ are each independently bonded atthe o-position or the m-position and one of R⁷, one of R⁸ and one of R⁹are each independently bonded at the p-position or the m-position, andit is more preferable that two of R⁷, two of R⁸ and two of R⁹ are eachindependently bonded at the m-position and one of R⁷, one of R⁸ and oneof R⁹ are each independently bonded at the p-position, with respect tothe bonding site of S⁺, respectively. When m7, m8 and m9 are 4, it ispreferable that two of R⁷, two of R⁸ and two of R⁹ are eachindependently bonded at the o-position or the m-position and two of R⁷,two of R⁸ and two of R⁹ are each independently bonded at the p-positionor the m-position, and it is more preferable that two of R⁷, two of R⁸and two of R⁹ are each independently bonded at the m-position, one ofR⁷, one of R⁸ and one of R⁹ are each independently bonded at theo-position and one of R⁷, one of R⁸ and one of R⁹ are each independentlybonded at the p-position, with respect to the bonding site of S⁺,respectively.

Examples of the cation (I) represented by formula (I-C) include a cationrepresented by formula (I-C-1) (hereinafter sometimes referred to as“cation (I-C-1)”):

wherein, in formula (I-C-1),

-   -   R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, m1, m2, m3, m4, m5, m6, m7,        m8 and m9 are the same as defined in formula (I).

L¹, L² and L³ each independently represent a hydrocarbon group having 1to 18 carbon atoms, the hydrocarbon group may have a substituent, and—CH₂— included in the hydrocarbon group may be replaced by —O—, —CO—,—S— or —SO₂—, and

-   -   X¹, X² and X³ each independently represent —O— or —S—.

Examples of the hydrocarbon group having 1 to 18 carbon atoms (thehydrocarbon group may have a substituent, and —CH₂— included in thehydrocarbon group may be replaced by —O—, —CO—, —S— or —SO₂—) as for L¹,L² and L³ include the same groups as mentioned for A¹, A² and A³ in therange of 1 to 18 carbon atoms.

X¹ is preferably —O—.

X² is preferably —O—.

X³ is preferably —O—.

The bonding site of X¹, X² and X³ to the benzene ring may be eachindependently the o-position, the m-position or the p-position, withrespect to the bonding site of S+, respectively. Particularly, when m1,m2 and m3 are 1, X¹, X² and X³ are each independently bonded preferablyat the p-position or the m-position, and more preferably at thep-position, with respect to the bonding site of S+, respectively. Whenm1, m2 and m3 are 2, it is preferable that one of X¹, one of X² and oneof X³ are each independently bonded at the o-position or the m-positionand one of X¹, one of X² and one of X³ are each independently bonded atthe o-position or the m-position, and it is more preferable that two ofX¹, two of X² and two of X³ are each independently bonded at them-position, with respect to the bonding site of S⁺, respectively. Whenm1, m2 and m3 are 3, it is preferable that two of X¹, two of X² and twoof X³ are each independently bonded at the o-position or the m-positionand one of X¹, one of X² and one of X³ are each independently bonded atthe p-position or the m-position, and it is more preferable that two ofX¹, two of X² and two of X³ are each independently bonded at them-position and one of X¹, one of X² and one of X³ are each independentlybonded at the p-position, with respect to the bonding site of S⁺,respectively. When m1, m2 and m3 are 4, it is preferable that two of X¹,two of X² and two of X³ are each independently bonded at the o-positionor the m-position and two of X¹, two of X² and two of X³ are eachindependently bonded at the p-position or the m-position, and it is morepreferable that two of X¹, two of X² and two of X³ are eachindependently bonded at the o-position and two of X¹, two of X² and twoof X3 are each independently bonded at the m-position, with respect tothe bonding site of S⁺, respectively.

Preferably, L¹, L² and L³ are each independently a hydrocarbon grouphaving 1 to 16 carbon atoms (—CH₂— included in the hydrocarbon group maybe replaced by —O—, —CO—, —S— or —SO₂—), more preferably a hydrocarbongroup having 1 to 14 carbon atoms (—CH₂— included in the hydrocarbongroup may be replaced by —O—, —CO—, —S— or —SO₂—), still more preferablya chain hydrocarbon group having 1 to 9 carbon atoms, an alicyclichydrocarbon group having 3 to 12 carbon atoms, or a group obtained bycombining a chain hydrocarbon group having 1 to 4 carbon atoms with analicyclic hydrocarbon group having 3 to 10 carbon atoms (—CH₂— includedin the chain hydrocarbon group and the alicyclic hydrocarbon group maybe replaced by —O—, —CO—, —S— or —SO₂—), yet more preferably analkanediyl group having 1 to 6 carbon atoms (—CH₂— included in thealkanediyl group may be replaced by —O— or —CO—), further preferably analkanediyl group having 1 to 4 carbon atoms (—CH₂— included in thealkanediyl group may be replaced by —O— or —CO—), and still furtherpreferably an alkanediyl group having 1 to 3 carbon atoms (—CH₂—included in the alkanediyl group may be replaced by —O— or —CO—). Ofthese, a methylene group, an ethane-1,1-diyl group, a propane-1,1-diylgroup, a propane-2,2-diyl group, a carbonyl group, a carbonyloxy group,a carbonyloxymethylene group, an ethyleneoxy group, amethylenecarbonyloxymethylene group or an ethyleneoxycarbonyl group ispreferable, and a methylene group is more preferable.

Examples of the cation (I) of the salt (I) include cations representedby the following formula (I-c-1) to formula (I-c-79).

[Anion (I)]

The anion (I) of a salt represented by formula (I) is an organic anionrepresented by AI⁻.

Examples of the organic anion represented by AI⁻ include a sulfonic acidanion, a sulfonylimide anion, a sulfonylmethide anion and a carboxylicacid anion. The organic anion represented by AI⁻ is preferably asulfonic acid anion, and more preferably an anion represented by formula(I-A):

wherein, in formula (I-A),

-   -   Q¹ and Q² each independently represent a hydrogen atom, a        fluorine atom, an alkyl group having 1 to 6 carbon atoms or a        perfluoroalkyl group having 1 to 6 carbon atoms,    -   L¹ represents a saturated hydrocarbon group having 1 to 24        carbon atoms, —CH₂— included in the saturated hydrocarbon group        may be replaced by —O— or —CO—, and a hydrogen atom included in        the saturated hydrocarbon group may be substituted with a        fluorine atom or a hydroxy group, and    -   Y¹ represents a methyl group which may have a substituent, or an        alicyclic hydrocarbon group having 3 to 24 carbon atoms which        may have a substituent, and —CH₂— included in the alicyclic        hydrocarbon group may be replaced by —O—, —S—, —SO₂— or —CO—.

In formula (I-A), when —CH₂— included in the saturated hydrocarbon groupis replaced by —O— or —CO—, the number of carbon atoms beforereplacement is taken as the number of carbon atoms of the saturatedhydrocarbon group. When —CH₂-included in the alicyclic hydrocarbon groupis replaced by O—, —S—, —SO₂— or —CO—, the number of carbon atoms beforereplacement is taken as the number of carbon atoms of the alicyclichydrocarbon group.

Examples of the perfluoroalkyl group having 1 to 6 carbon atoms as forQ¹ and Q² include a trifluoromethyl group, a perfluoroethyl group, aperfluoropropyl group, a perfluoroisopropyl group, a perfluorobutylgroup, a perfluorosec-butyl group, a perfluorotert-butyl group, aperfluoropentyl group and a perfluorohexyl group.

Examples of the alkyl group as for Q¹ and Q² include a methyl group, anethyl group, a propyl group, an isopropyl group, a butyl group, asec-butyl group, a tert-butyl group, a pentyl group, a hexyl group andthe like.

Preferably, at least one of Q¹ and Q² comprises a fluorine atom or aperfluoroalkyl group, more preferably at least one of Q¹ or Q² is afluorine atom or a perfluoroalkyl group, still more preferably, Q¹ or Q²are each independently a fluorine atom or a trifluoromethyl group, andyet more preferably, both are fluorine atoms.

Examples of the divalent saturated hydrocarbon group in L¹ include alinear alkanediyl group, a branched alkanediyl group, a monocyclic orpolycyclic divalent alicyclic saturated hydrocarbon group, or thedivalent saturated hydrocarbon group may be a group formed by combiningtwo or more of these groups.

Specific examples thereof include linear alkanediyl groups such as amethylene group, an ethylene group, a propane-1,3-diyl group, abutane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diylgroup, a heptane-1,7-diyl group, an octane-1,8-diyl group, anonane-1,9-diyl group, a decane-1,10-diyl group, an undecane-1,11-diylgroup, a dodecane-1,12-diyl group, a tridecane-1,13-diyl group, atetradecane-1,14-diyl group, a pentadecane-1,15-diyl group, ahexadecane-1,16-diyl group and a heptadecane-1,17-diyl group;

-   -   branched alkanediyl groups such as an ethane-1,1-diyl group, a        propane-1,1-diyl group, a propane-1,2-diyl group, a        propane-2,2-diyl group, a pentane-2,4-diyl group, a        2-methylpropane-1,3-diyl group, a 2-methylpropane-1,2-diyl        group, a pentane-1,4-diyl group and a 2-methylbutane-1,4-diyl        group;    -   monocyclic divalent alicyclic saturated hydrocarbon groups such        as a cyclobutane-1,3-diyl group, a cyclopentane-1,3-diyl group,        a cyclohexane-1,4-diyl group and a cyclooctane-1,5-diyl group;        and    -   polycyclic divalent alicyclic saturated hydrocarbon groups such        as a norbornane-1,4-diyl group, a norbornane-2,5-diyl group, an        adamantane-1,5-diyl group and an adamantane-2,6-diyl group.

The group in which —CH₂— included in the divalent saturated hydrocarbongroup represented by L¹ is replaced by —O— or —CO— includes, forexample, a group represented by any one of formula (b1-1) to formula(b1-3). In groups represented by formula (b1-1) to formula (b1-3) andgroups represented by formula (b1-4) to formula (b1-11) which arespecific examples thereof, * and ** represent a bonding site, and *represents a bonding site to —Y¹.

In formula (b1-1),

-   -   L^(b2) represents a single bond or a divalent saturated        hydrocarbon group having 1 to 22 carbon atoms, and a hydrogen        atom included in the saturated hydrocarbon group may be        substituted with a fluorine atom,    -   L^(b3) represents a single bond or a divalent saturated        hydrocarbon group having 1 to 22 carbon atoms, a hydrogen atom        included in the saturated hydrocarbon group may be substituted        with a fluorine atom or a hydroxy group, and —CH₂— included in        the saturated hydrocarbon group may be replaced by —O— or —CO—,        and    -   the total number of carbon atoms of L^(b2) and L^(b3) is 22 or        less.

In formula (b1-2),

-   -   L^(b4) represents a single bond or a divalent saturated        hydrocarbon group having 1 to 22 carbon atoms, and a hydrogen        atom included in the saturated hydrocarbon group may be        substituted with a fluorine atom,    -   L^(b5) represents a single bond or a divalent saturated        hydrocarbon group having 1 to 22 carbon atoms, a hydrogen atom        included in the saturated hydrocarbon group may be substituted        with a fluorine atom or a hydroxy group, and —CH₂— included in        the saturated hydrocarbon group may be replaced by —O— or —CO—,        and    -   the total number of carbon atoms of L^(b4) and L^(b5) is 22 or        less.

In formula (b1-3),

-   -   L^(b6) represents a single bond or a divalent saturated        hydrocarbon group having 1 to 23 carbon atoms, a hydrogen atom        included in the saturated hydrocarbon group may be substituted        with a fluorine atom or a hydroxy group,    -   L^(b7) represents a single bond or a divalent saturated        hydrocarbon group having 1 to 23 carbon atoms, a hydrogen atom        included in the saturated hydrocarbon group may be substituted        with a fluorine atom or a hydroxy group, and —CH₂— included in        the saturated hydrocarbon group may be replaced by —O— or —CO—,        and    -   the total number of carbon atoms of L^(b6) and L^(b7) is 23 or        less.

In groups represented by formula (b1-1) to formula (b1-3), when —CH₂—included in the saturated hydrocarbon group is replaced by —O— or —CO—,the number of carbon atoms before replacement is taken as the number ofcarbon atoms of the saturated hydrocarbon group.

Examples of the divalent saturated hydrocarbon group include those whichare the same as the divalent saturated hydrocarbon group of L¹.

L^(b2) is preferably a single bond, a methylene group, —CH(CF₃)— or—C(CF₃)₂—.

L^(b3) is preferably a divalent saturated hydrocarbon group having 1 to4 carbon atoms.

L^(b4) is preferably a divalent saturated hydrocarbon group having 1 to8 carbon atoms, and a hydrogen atom included in the divalent saturatedhydrocarbon group may be substituted with a fluorine atom, and morepreferably a methylene group, —CH(CF₃)— or —C(CF₃)₂—.

L^(b5) is preferably a single bond or a divalent saturated hydrocarbongroup having 1 to 8 carbon atoms.

L^(b6) is preferably a single bond or a divalent saturated hydrocarbongroup having 1 to 4 carbon atoms, and a hydrogen atom included in thesaturated hydrocarbon group may be substituted with a fluorine atom.

L^(b7) is preferably a single bond or a divalent saturated hydrocarbongroup having 1 to 18 carbon atoms, a hydrogen atom included in thesaturated hydrocarbon group may be substituted with a fluorine atom or ahydroxy group, and —CH₂— included in the divalent saturated hydrocarbongroup may be replaced by —O— or —CO—.

The group in which —CH₂— included in the divalent saturated hydrocarbongroup represented by L¹ is replaced by —O— or —CO— is preferably a grouprepresented by formula (b1-1) or formula (b1-3).

Examples of the group represented by formula (b1-1) include groupsrepresented by formula (b1-4) to formula (b1-8).

In formula (b1-4),

-   -   L^(b8) represents a single bond or a divalent saturated        hydrocarbon group having 1 to 22 carbon atoms, and a hydrogen        atom included in the saturated hydrocarbon group may be        substituted with a fluorine atom or a hydroxy group.

In formula (b1-5),

-   -   L^(b9) represents a divalent saturated hydrocarbon group having        1 to 20 carbon atoms, and —CH₂— included in the divalent        saturated hydrocarbon group may be replaced by —O— or —CO—.

L^(b10) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 19 carbon atoms, and a hydrogen atom included in thedivalent saturated hydrocarbon group may be substituted with a fluorineatom or a hydroxy group, and

-   -   the total number of carbon atoms of L^(b9) and L^(b10) is 20 or        less.

In formula (b1-6),

-   -   L^(b11) represents a divalent saturated hydrocarbon group having        1 to 21 carbon atoms,    -   L^(b12) represents a single bond or a divalent saturated        hydrocarbon group having 1 to 20 carbon atoms, and a hydrogen        atom included in the divalent saturated hydrocarbon group may be        substituted with a fluorine atom or a hydroxy group, and    -   the total number of carbon atoms of L^(b11) and L^(b12) is 21 or        less.

In formula (b1-7),

-   -   L^(b13) represents a divalent saturated hydrocarbon group having        1 to 19 carbon atoms,    -   L^(b14) represents a single bond or a divalent saturated        hydrocarbon group having 1 to 18 carbon atoms, and —CH₂—        included in the divalent saturated hydrocarbon group may be        replaced by —O— or —CO—,    -   L^(b15) represents a single bond or a divalent saturated        hydrocarbon group having 1 to 18 carbon atoms, and a hydrogen        atom included in the divalent saturated hydrocarbon group may be        substituted with a fluorine atom or a hydroxy group, and    -   the total number of carbon atoms of L^(b13) to L^(b15) is 19 or        less.

In formula (b1-8),

-   -   L^(b16) represents a divalent saturated hydrocarbon group having        1 to 18 carbon atoms, and —CH₂— included in the divalent        saturated hydrocarbon group may be replaced by —O— or —CO—,    -   L^(b17) represents a divalent saturated hydrocarbon group having        1 to 18 carbon atoms,    -   L^(b18) represents a single bond or a divalent saturated        hydrocarbon group having 1 to 17 carbon atoms, and a hydrogen        atom included in the divalent saturated hydrocarbon group may be        substituted with a fluorine atom or a hydroxy group, and    -   the total number of carbon atoms of L^(b16) to L^(b18) is 19 or        less.

L^(b8) is preferably a divalent saturated hydrocarbon group having 1 to4 carbon atoms.

L^(b9) is preferably a divalent saturated hydrocarbon group having 1 to8 carbon atoms.

L^(b10) is preferably a single bond or a divalent saturated hydrocarbongroup having 1 to 19 carbon atoms, and more preferably a single bond ora divalent saturated hydrocarbon group having 1 to 8 carbon atoms.

L^(b11) is preferably a divalent saturated hydrocarbon group having 1 to8 carbon atoms.

L^(b12) is preferably a single bond or a divalent saturated hydrocarbongroup having 1 to 8 carbon atoms.

L^(b13) is preferably a divalent saturated hydrocarbon group having 1 to12 carbon atoms.

L^(b14) is preferably a single bond or a divalent saturated hydrocarbongroup having 1 to 6 carbon atoms.

L^(b15) is preferably a single bond or a divalent saturated hydrocarbongroup having 1 to 18 carbon atoms, and more preferably a single bond ora divalent saturated hydrocarbon group having 1 to 8 carbon atoms.

L^(b16) is preferably a divalent saturated hydrocarbon group having 1 to12 carbon atoms.

L^(b17) is preferably a divalent saturated hydrocarbon group having 1 to6 carbon atoms.

L^(b18) is preferably a single bond or a divalent saturated hydrocarbongroup having 1 to 17 carbon atoms, and more preferably a single bond ora divalent saturated hydrocarbon group having 1 to 4 carbon atoms.

Examples of the group represented by formula (b1-3) include groupsrepresented by formula (b1-9) to formula (b1-11).

In formula (b1-9),

-   -   L^(b19) represents a single bond or a divalent saturated        hydrocarbon group having 1 to 23 carbon atoms, and a hydrogen        atom included in the saturated hydrocarbon group may be        substituted with a fluorine atom,    -   L^(b20) represents a single bond or a divalent saturated        hydrocarbon group having 1 to 23 carbon atoms, and a hydrogen        atom included in the saturated hydrocarbon group may be        substituted with a fluorine atom, a hydroxy group or an        alkylcarbonyloxy group, —CH₂— included in the alkylcarbonyloxy        group may be replaced by —O— or —CO—, and a hydrogen atom        included in the alkylcarbonyloxy group may be substituted with a        hydroxy group, and    -   the total number of carbon atoms of L^(b19) and L^(b20) is 23 or        less.

In formula (b1-10),

-   -   L^(b21) represents a single bond or a divalent saturated        hydrocarbon group having 1 to 21 carbon atoms, and a hydrogen        atom included in the saturated hydrocarbon group may be        substituted with a fluorine atom,    -   L^(b22) represents a single bond or a divalent saturated        hydrocarbon group having 1 to 21 carbon atoms,    -   L^(b23) represents a single bond or a divalent saturated        hydrocarbon group having 1 to 21 carbon atoms, and a hydrogen        atom included in the saturated hydrocarbon group may be        substituted with a fluorine atom, a hydroxy group or an        alkylcarbonyloxy group, —CH₂— included in the alkylcarbonyloxy        group may be replaced by —O— or —CO—, and a hydrogen atom        included in the alkylcarbonyloxy group may be substituted with a        hydroxy group, and    -   the total number of carbon atoms of L^(b21), L^(b22) and L^(b23)        is 21 or less.

In formula (b1-11),

-   -   L^(b24) represents a single bond or a divalent saturated        hydrocarbon group having 1 to 20 carbon atoms, and a hydrogen        atom included in the saturated hydrocarbon group may be        substituted with a fluorine atom,    -   L^(b25) represents a divalent saturated hydrocarbon group having        1 to 21 carbon atoms,    -   L^(b26) represents a single bond or a divalent saturated        hydrocarbon group having 1 to 20 carbon atoms, a hydrogen atom        included in the saturated hydrocarbon group may be substituted        with a fluorine atom, a hydroxy group or an alkylcarbonyloxy        group, —CH₂— included in the alkylcarbonyloxy group may be        replaced by —O— or —CO—, and a hydrogen atom included in the        alkylcarbonyloxy group may be substituted with a hydroxy group,        and    -   in which, the total number of carbon atoms of L^(b24), L^(b25)        and L^(b26) is 21 or less.

In the group represented by formula (b1-9) to the group represented byformula (b1-11), when a hydrogen atom included in the saturatedhydrocarbon group is substituted with an alkylcarbonyloxy group, thenumber of carbon atoms before replacement is taken as the number ofcarbon atoms of the saturated hydrocarbon group.

Examples of the alkylcarbonyloxy group include an acetyloxy group, apropionyloxy group, a butyryloxy group, a cyclohexylcarbonyloxy group,an adamantylcarbonyloxy group and the like.

Examples of the group represented by formula (b1-4) include thefollowings.

Examples of the group represented by formula (b1-5) include thefollowings.

Examples of the group represented by formula (b1-6) include thefollowings.

Examples of the group represented by formula (b1-7) include thefollowings.

Examples of the group represented by formula (b1-8) include thefollowings.

Examples of the group represented by formula (b1-2) include thefollowings.

Examples of the group represented by formula (b1-9) include thefollowings.

Examples of the group represented by formula (b1-10) include thefollowings.

Examples of the group represented by formula (b1-1) include thefollowings.

Examples of the alicyclic hydrocarbon group in which —CH₂— included inthe alicyclic hydrocarbon group represented by Y¹ is not replaced by—O—, —S—, —SO₂— or —CO— include groups represented by formula (Y1) toformula (Y11) and formula (Y36) to formula (Y38).

When —CH₂— included in the alicyclic hydrocarbon group represented by Y1is replaced by —O—, —S—, —SO₂— or —CO—, the number may be 1, or 2 ormore. Examples of such group include groups represented by formula (Y12)to formula (Y35) and formula (Y39) to formula (Y43). —O— or —CO— of thegroups represented by formula (Y12) to formula (Y35) and formula (Y39)to formula (Y43) may be replaced by —S— or —SO₂—. * represents a bondingsite to L¹.

The alicyclic hydrocarbon group represented by Y¹ is preferably a grouprepresented by any one of formula (Y1) to formula (Y20), formula (Y26),formula (Y27), formula (Y30), formula (Y31) and formula (Y39) to formula(Y43), more preferably a group represented by formula (Y11), formula(Y15), formula (Y16), formula (Y20), formula (Y26), formula (Y27),formula (Y30), formula (Y31), formula (Y39), formula (Y40), formula(Y42) or formula (Y43), and still more preferably a group represented byformula (Y11), formula (Y15), formula (Y20), formula (Y26), formula(Y27), formula (Y30), formula (Y31), formula (Y39), formula (Y40),formula (Y42) or formula (Y43).

When the alicyclic hydrocarbon group represented by Y1 is a spiro ringhaving an oxygen atom, such as formula (Y28) to formula (Y35), formula(Y39), formula (Y40), formula (Y42) or formula (Y43), the alkanediylgroup between two oxygen atoms preferably has one or more fluorineatoms. Of alkanediyl groups included in a ketal structure, it ispreferable that a methylene group adjacent to the oxygen atom is notsubstituted with a fluorine atom.

Examples of the substituent of the methyl group represented by Y¹include a halogen atom, a hydroxy group, an alicyclic hydrocarbon grouphaving 3 to 16 carbon atoms, an aromatic hydrocarbon group having 6 to18 carbon atoms, a glycidyloxy group, a —(CH₂)_(ja)—CO—O—R^(b1) group ora —(CH₂)_(ja)—O—CO—R^(b1) group (wherein R^(b1) represents an alkylgroup having 1 to 16 carbon atoms, an alicyclic hydrocarbon group having3 to 16 carbon atoms, an aromatic hydrocarbon group having 6 to 18carbon atoms, or a group obtained by combining these groups. jarepresents an integer of 0 to 4. —CH₂— included in the alkyl group andthe alicyclic hydrocarbon group may be replaced by —O—, —SO₂— or —CO—,and a hydrogen atom included in the alkyl group, the alicyclichydrocarbon group and the aromatic hydrocarbon group may be substitutedwith a hydroxy group or a fluorine atom).

Examples of the substituent of the alicyclic hydrocarbon grouprepresented by Y1 include a halogen atom, a hydroxy group, an alkylgroup having 1 to 16 carbon atoms which may be substituted with ahydroxy group (—CH₂— included in the alkyl group may be replaced by —O—or —CO—), an alicyclic hydrocarbon group having 3 to 16 carbon atoms, anaromatic hydrocarbon group having 6 to 18 carbon atoms, an aralkyl grouphaving 7 to 21 carbon atoms, a glycidyloxy group, a—(CH₂)_(ja)—CO—O—R^(b1) group or a —(CH₂)_(ja)—O—CO—R^(b1) group(wherein R^(b1) represents an alkyl group having 1 to 16 carbon atoms,an alicyclic hydrocarbon group having 3 to 16 carbon atoms, an aromatichydrocarbon group having 6 to 18 carbon atoms, or a group obtained bycombining these groups. ja represents an integer of 0 to 4. —CH₂—included in the alkyl group and the alicyclic hydrocarbon group may bereplaced by —O—, —SO₂— or —CO—, and a hydrogen atom included in thealkyl group, the alicyclic hydrocarbon group and the aromatichydrocarbon group may be substituted with a hydroxy group or a fluorineatom).

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom.

Examples of the alicyclic hydrocarbon group include a cyclopentyl group,a cyclohexyl group, a methylcyclohexyl group, a dimethylcyclohexylgroup, a cycloheptyl group, a cyclooctyl group, a norbornyl group, anadamantyl group and the like. The alicyclic hydrocarbon group may have achain hydrocarbon group, and examples thereof include a methylcyclohexylgroup, a dimethylcyclohexyl group and the like. The number of carbonatoms of the alicyclic hydrocarbon group is preferably 3 to 12, and morepreferably 3 to 10.

Examples of the aromatic hydrocarbon group include aryl groups such as aphenyl group, a naphthyl group, an anthryl group, a biphenyl group and aphenanthryl group. The aromatic hydrocarbon group may have a chainhydrocarbon group or an alicyclic hydrocarbon group, and it is possibleto exemplify aromatic hydrocarbon groups which have a chain hydrocarbongroup having 1 to 18 carbon atoms (a tolyl group, a xylyl group, acumenyl group, a mesityl group, a p-methylphenyl group, a p-ethylphenylgroup, a p-tert-butylphenyl group, a 2,6-diethylphenyl group, a2-methyl-6-ethylphenyl group, etc.) and aromatic hydrocarbon groupswhich have an alicyclic hydrocarbon group having 3 to 18 carbon atoms (ap-cyclohexylphenyl group, a p-adamantylphenyl group, etc.). The numberof carbon atoms of the aromatic hydrocarbon group is preferably 6 to 14,and more preferably 6 to 10.

Examples of the alkyl group include a methyl group, an ethyl group, apropyl group, an isopropyl group, a butyl group, a sec-butyl group, atert-butyl group, a pentyl group, a hexyl group, a heptyl group, a2-ethylhexyl group, an octyl group, a nonyl group, a decyl group, anundecyl group, a dodecyl group and the like. The number of carbon atomsof the alkyl group is preferably 1 to 12, more preferably 1 to 6, andstill more preferably 1 to 4.

Examples of the alkyl group substituted with a hydroxy group includehydroxyalkyl groups such as a hydroxymethyl group and a hydroxyethylgroup.

Examples of the aralkyl group include a benzyl group, a phenethyl group,a phenylpropyl group, a naphthylmethyl group and a naphthylethyl group.

Examples of the group in which —CH₂— included in the alkyl group isreplaced by —O—, —SO₂— or —CO— include an alkoxy group, an alkylsulfonylgroup, an alkoxycarbonyl group, an alkylcarbonyl group, analkylcarbonyloxy group, or a group obtained by combining these groups.

Examples of the alkoxy group include a methoxy group, an ethoxy group, apropoxy group, a butoxy group, a pentyloxy group, a hexyloxy group, aheptyloxy group, an octyloxy group, a decyloxy group and a dodecyloxygroup. The number of carbon atoms of the alkoxy group is preferably 1 to12, more preferably 1 to 6, and still more preferably 1 to 4.

Examples of the alkylsulfonyl group include a methylsulfonyl group, anethylsulfonyl group, a propylsulfonyl group and the like. The number ofcarbon atoms of the alkylsulfonyl group is preferably 1 to 12, morepreferably 1 to 6, and still more preferably 1 to 4.

Examples of the alkoxycarbonyl group include a methoxycarbonyl group, anethoxycarbonyl group, a butoxycarbonyl group and the like. The number ofcarbon atoms of the alkoxycarbonyl group is preferably 2 to 12, morepreferably 2 to 6, and still more preferably 2 to 4.

Examples of the alkylcarbonyl group include an acetyl group, a propionylgroup and a butyryl group. The number of carbon atoms of thealkylcarbonyl group is preferably 2 to 12, more preferably 2 to 6, andstill more preferably 2 to 4.

Examples of the alkylcarbonyloxy group include an acetyloxy group, apropionyloxy group, a butyryloxy group and the like. The number ofcarbon atoms of the alkylcarbonyloxy group is preferably 2 to 12, morepreferably 2 to 6, and still more preferably 2 to 4.

Examples of the combined group include a group obtained by combining analkoxy group with an alkyl group, a group obtained by combining analkoxy group with an alkoxy group, a group obtained by combining analkoxy group with an alkylcarbonyl group, a group obtained by combiningan alkoxy group with an alkylcarbonyloxy group and the like.

Examples of the group obtained by combining an alkoxy group with analkyl group include alkoxyalkyl groups such as a methoxymethyl group, amethoxyethyl group, an ethoxyethyl group, an ethoxymethyl group and thelike. The number of carbon atoms of the alkoxyalkyl group is preferably2 to 12, more preferably 2 to 6, and still more preferably 2 to 4.

Examples of the group obtained by combining an alkoxy group with analkoxy group include alkoxyalkoxy groups such as a methoxymethoxy group,a methoxyethoxy group, an ethoxymethoxy group, an ethoxyethoxy group andthe like. The number of carbon atoms of the alkoxyalkoxy group ispreferably 2 to 12, more preferably 2 to 6, and still more preferably 2to 4.

Examples of the group obtained by combining an alkoxy group with analkylcarbonyl group include alkoxyalkylcarbonyl groups such as amethoxyacetyl group, a methoxypropionyl group, an ethoxyacetyl group, anethoxypropionyl group and the like. The number of carbon atoms of thealkoxyalkylcarbonyl group is preferably 3 to 13, more preferably 3 to 7,and still more preferably 3 to 5.

Examples of the group obtained by combining an alkoxy group with analkylcarbonyloxy group include alkoxyalkylcarbonyloxy groups such as amethoxyacetyloxy group, a methoxypropionyloxy group, an ethoxyacetyloxygroup, an ethoxypropionyloxy group and the like. The number of carbonatoms of the alkoxyalkylcarbonyloxy group is preferably 3 to 13, morepreferably 3 to 7, and still more preferably 3 to 5.

Examples of the group in which —CH₂— included in the alicyclichydrocarbon group is replaced by —O—, —SO₂— or —CO— include groupsrepresented by formula (Y12) to formula (Y35), formula (Y39) to formula(Y43) and the like.

Y¹ is preferably an alicyclic hydrocarbon group having 3 to 24 carbonatoms which may have a substituent, more preferably an alicyclichydrocarbon group having 3 to 20 carbon atoms which may have asubstituent, still more preferably an alicyclic hydrocarbon group having3 to 18 carbon atoms which may have a substituent, yet more preferablyan adamantyl group which may have a substituent or a norbornyl groupwhich may have a substituent, and —CH₂— constituting the alicyclichydrocarbon group, the adamantyl group or the norbornyl group may bereplaced by —O—, —S—, —SO₂— or —CO—. Specific examples include thefollowings.

Of these, Y¹ is preferably an adamantyl group, a hydroxyadamantyl group,an oxoadamantyl group, a norbornanelactone group or a group representedby each of formula (Y42), formula (Y100) to formula (Y114) and formula(Y134) to formula (Y139), and particularly preferably a hydroxyadamantylgroup, an oxoadamantyl group, a group including these groups, or a grouprepresented by each of formula (Y42), formula (Y100) to formula (Y114)and formula (Y134) to formula (Y139).

The anion represented by formula (I-A) is preferably anions representedby formula (I-A-1) to formula (I-A-62) [hereinafter sometimes referredto as “anion (I-A-1)” according to the number of formula], and morepreferably an anion represented by any one of formula (I-A-1) to formula(I-A-4), formula (I-A-9), formula (I-A-10), formula (I-A-24) to formula(I-A-33), formula (I-A-36) to formula (I-A-40) and formula (I-A-47) toformula (I-A-62)).

R^(i2) to R^(i7) each independently represent, for example, an alkylgroup having 1 to 4 carbon atoms, and preferably a methyl group or anethyl group. R^(i8) is, for example, a chain hydrocarbon group having 1to 12 carbon atoms, preferably an alkyl group having 1 to 4 carbonatoms, an alicyclic hydrocarbon group having 5 to 12 carbon atoms, orgroups formed by combining these groups, and more preferably a methylgroup, an ethyl group, a cyclohexyl group or an adamantyl group. L^(A41)is a single bond or an alkanediyl group having 1 to 4 carbon atoms. Q¹and Q² are the same as defined above.

Specific examples of the anion represented by formula (I-A) includeanions mentioned in JP 2010-204646 A.

Preferable anions represented by formula (I-A) are anions represented byformula (I-a-1) to formula (I-a-40).

Of these, an anion represented by any one of formula (I-a-1) to formula(I-a-4), formula (I-a-7) to formula (I-a-11), formula (I-a-14) toformula (I-a-30) and formula (I-a-35) to formula (I-a-40) is preferable.

Examples of the sulfonylimide anion represented by AI⁻ include thefollowings.

Examples of the sulfonylmethide anion represented by AI⁻ include thefollowings.

Examples of the carboxylic acid anion represented by AI⁻ include thefollowings.

Specific examples of the salt (I) include salts obtained by optionallycombining the above-mentioned cations and anions. Specific examples ofthe salt (I) are shown in the following table.

In the following table, the respective symbols represent symbolsimparted to structures showing the above-mentioned anions and cations,and “to” indicates that each of the salt (I) and the anion (I) or thecation (I) corresponds to each other. For example, the salt (I-1)indicates a salt composed of an anion represented by formula (I-a-1) anda cation represented by formula (I-c-1), the salt (I-2) indicates a saltcomposed of an anion represented by formula (I-a-2) and a cationrepresented by formula (I-c-1), and the salt (I-39) indicates a saltcomposed of an anion represented by formula (I-a-1) and a cationrepresented by formula (I-c-2). The salt (I-3003) indicates a saltcomposed of an anion represented by formula (I-a-39) and a cationrepresented by formula (I-c-1), the salt (I-3004) indicates a saltcomposed of an anion represented by formula (I-a-39) and a cationrepresented by formula (I-c-2), and the salt (I-3082) indicates a saltcomposed of an anion represented by formula (I-a-40) and a cationrepresented by formula (I-c-1).

TABLE 1 Salt (I) Anion (I) Cation (I) (I-1) to (I-38) (I-a-1) to(I-a-38) (I-c-1) (I-39) to (I-76) (I-a-1) to (I-a-38) (I-c-2) (I-77) to(I-114) (I-a-1) to (I-a-38) (I-c-3) (I-115) to (I-152) (I-a-1) to(I-a-38) (I-c-4) (I-153) to (I-190) (I-a-1) to (I-a-38) (I-c-5) (I-191)to (I-228) (I-a-1) to (I-a-38) (I-c-6) (I-229) to (I-266) (I-a-1) to(I-a-38) (I-c-7) (I-267) to (I-304) (I-a-1) to (I-a-38) (I-c-8) (I-305)to (I-342) (I-a-1) to (I-a-38) (I-c-9) (I-343) to (I-380) (I-a-1) to(I-a-38) (I-c-10) (I-381) to (I-418) (I-a-1) to (I-a-38) (I-c-11)(I-419) to (I-456) (I-a-1) to (I-a-38) (I-c-12) (I-457) to (I-494)(I-a-1) to (I-a-38) (I-c-13) (I-495) to (I-532) (I-a-1) to (I-a-38)(I-c-14) (I-533) to (I-570) (I-a-1) to (I-a-38) (I-c-15) (I-571) to(I-608) (I-a-1) to (I-a-38) (I-c-16) (I-609) to (I-646) (I-a-1) to(I-a-38) (I-c-17) (I-647) to (I-684) (I-a-1) to (I-a-38) (I-c-18)(I-685) to (I-722) (I-a-1) to (I-a-38) (I-c-19) (I-723) to (I-760)(I-a-1) to (I-a-38) (I-c-20) (I-761) to (I-798) (I-a-1) to (I-a-38)(I-c-21) (I-799) to (I-836) (I-a-1) to (I-a-38) (I-c-22) (I-837) to(I-874) (I-a-1) to (I-a-38) (I-c-23) (I-875) to (I-912) (I-a-1) to(I-a-38) (I-c-24) (I-913) to (I-950) (I-a-1) to (I-a-38) (I-c-25)(I-951) to (I-988) (I-a-1) to (I-a-38) (I-c-26) (I-989) to (I-1026)(I-a-1) to (I-a-38) (I-c-27) (I-1027) to (I-1064) (I-a-1) to (I-a-38)(I-c-28) (I-1065) to (I-1102) (I-a-1) to (I-a-38) (I-c-29) (I-1103) to(I-1140) (I-a-1) to (I-a-38) (I-c-30) (I-1141) to (I-1178) (I-a-1) to(I-a-38) (I-c-31) (I-1179) to (I-1216) (I-a-1) to (I-a-38) (I-c-32)(I-1217) to (I-1254) (I-a-1) to (I-a-38) (I-c-33) (I-1255) to (I-1292)(I-a-1) to (I-a-38) (I-c-34) (I-1293) to (I-1330) (I-a-1) to (I-a-38)(I-c-35) (I-1331) to (I-1368) (I-a-1) to (I-a-38) (I-c-36) (I-1369) to(I-1406) (I-a-1) to (I-a-38) (I-c-37) (I-1407) to (I-1444) (I-a-1) to(I-a-38) (I-c-38) (I-1445) to (I-1482) (I-a-1) to (I-a-38) (I-c-39)(I-1483) to (I-1520) (I-a-1) to (I-a-38) (I-c-40) (I-1521) to (I-1558)(I-a-1) to (I-a-38) (I-c-41) (I-1559) to (I-1596) (I-a-1) to (I-a-38)(I-c-42) (I-1597) to (I-1634) (I-a-1) to (I-a-38) (I-c-43) (I-1635) to(I-1672) (I-a-1) to (I-a-38) (I-c-44) (I-1673) to (I-1710) (I-a-1) to(I-a-38) (I-c-45) (I-1711) to (I-1748) (I-a-1) to (I-a-38) (I-c-46)(I-1749) to (I-1786) (I-a-1) to (I-a-38) (I-c-47) (I-1787) to (I-1824)(I-a-1) to (I-a-38) (I-c-48) (I-1825) to (I-1862) (I-a-1) to (I-a-38)(I-c-49) (I-1863) to (I-1900) (I-a-1) to (I-a-38) (I-c-50) (I-1901) to(I-1938) (I-a-1) to (I-a-38) (I-c-51) (I-1939) to (I-1976) (I-a-1) to(I-a-38) (I-c-52) (I-1977) to (I-2014) (I-a-1) to (I-a-38) (I-c-53)(I-2015) to (I-2052) (I-a-1) to (I-a-38) (I-c-54) (I-2053) to (I-2090)(I-a-1) to (I-a-38) (I-c-55) (I-2091) to (I-2128) (I-a-1) to (I-a-38)(I-c-56) (I-2129) to (I-2166) (I-a-1) to (I-a-38) (I-c-57) (I-2167) to(I-2204) (I-a-1) to (I-a-38) (I-c-58) (I-2205) to (I-2242) (I-a-1) to(I-a-38) (I-c-59) (I-2243) to (I-2280) (I-a-1) to (I-a-38) (I-c-60)(I-2281) to (I-2318) (I-a-1) to (I-a-38) (I-c-61) (I-2319) to (I-2356)(I-a-1) to (I-a-38) (I-c-62) (I-2357) to (I-2394) (I-a-1) to (I-a-38)(I-c-63) (I-2395) to (I-2432) (I-a-1) to (I-a-38) (I-c-64) (I-2433) to(I-2470) (I-a-1) to (I-a-38) (I-c-65) (I-2471) to (I-2508) (I-a-1) to(I-a-38) (I-c-66) (I-2509) to (I-2546) (I-a-1) to (I-a-38) (I-c-67)(I-2547) to (I-2584) (I-a-1) to (I-a-38) (I-c-68) (I-2585) to (I-2622)(I-a-1) to (I-a-38) (I-c-69) (I-2623) to (I-2660) (I-a-1) to (I-a-38)(I-c-70) (I-2661) to (I-2698) (I-a-1) to (I-a-38) (I-c-71) (I-2699) to(I-2736) (I-a-1) to (I-a-38) (I-c-72) (I-2737) to (I-2774) (I-a-1) to(I-a-38) (I-c-73) (I-2775) to (I-2812) (I-a-1) to (I-a-38) (I-c-74)(I-2813) to (I-2850) (I-a-1) to (I-a-38) (I-c-75) (I-2851) to (I-2888)(I-a-1) to (I-a-38) (I-c-76) (I-2889) to (I-2926) (I-a-1) to (I-a-38)(I-c-77) (I-2927) to (I-2964) (I-a-1) to (I-a-38) (I-c-78) (I-2965) to(I-3002) (I-a-1) to (I-a-38) (I-c-79) (I-3003) to (I-3081) (I-a-39)(I-c-1) to (I-c-79) (I-3082) to (I-3160) (I-a-40) (I-c-1) to (I-c-79)

Of these, the salt (I) is preferably a salt obtained by combining ananion represented by any one of formula (I-a-1) to formula (I-a-4),formula (I-a-7) to formula (I-a-11), formula (I-a-14) to formula(I-a-30) and formula (I-a-35) to formula (I-a-40) with a cationrepresented by any one of formula (I-c-1) to formula (I-c-79), andspecifically, the salt (I) preferably includes salt (I-1) to salt (I-4),salt (I-7) to salt (I-11), salt (I-14) to salt (I-30), salt (I-35) tosalt (1-38), salt (I-39) to salt (1-42), salt (I-45) to salt (1-49),salt (I-52) to salt (1-68), salt (I-73) to salt (1-76), salt (I-77) tosalt (1-80), salt (I-83) to salt (I-87), salt (I-90) to salt (1-106),salt (I-111) to salt (I-114), salt (I-115) to salt (I-118), salt (I-121)to salt (I-125), salt (I-128) to salt (I-144), salt (I-149) to salt(I-152), salt (I-153) to salt (1-156), salt (I-159) to salt (I-163),salt (I-166) to salt (I-182), salt (I-187) to salt (I-190), salt (I-191)to salt (I-194), salt (I-197) to salt (I-201), salt (I-204) to salt(I-220), salt (I-225) to salt (I-228), salt (I-229) to salt (I-232),salt (I-235) to salt (I-239), salt (I-242) to salt (I-258), salt (I-263)to salt (I-266), salt (I-267) to salt (I-270), salt (I-273) to salt(I-277), salt (I-280) to salt (I-296), salt (I-301) to salt (I-304),salt (I-305) to salt (I-308), salt (I-311) to salt (I-315), salt (I-318)to salt (I-334), salt (I-339) to salt (I-342), salt (I-343) to salt(1-346), salt (I-349) to salt (I-353), salt (I-356) to salt (1-372),salt (I-377) to salt (I-380), salt (I-381) to salt (I-384), salt (I-387)to salt (I-391), salt (I-394) to salt (I-410), salt (I-415) to salt(I-418), salt (I-419) to salt (1-422), salt (I-425) to salt (I-429),salt (I-432) to salt (1-448), salt (I-453) to salt (I-456), salt (I-457)to salt (I-460), salt (I-463) to salt (I-467), salt (I-470) to salt(I-486), salt (I-491) to salt (I-494), salt (I-495) to salt (I-498),salt (I-501) to salt (I-505), salt (I-508) to salt (I-524), salt (I-529)to salt (I-532), salt (I-533) to salt (I-536), salt (I-539) to salt(I-543), salt (I-546) to salt (I-562), salt (I-567) to salt (I-570),salt (I-571) to salt (I-574), salt (I-577) to salt (I-581), salt (I-584)to salt (I-600), salt (I-605) to salt (I-608), salt (I-609) to salt(I-612), salt (I-615) to salt (I-619), salt (I-622) to salt (I-638),salt (I-643) to salt (I-646), salt (I-647) to salt (I-650), salt (I-653)to salt (I-657), salt (I-660) to salt (I-676), salt (I-681) to salt(I-684), salt (I-685) to salt (I-688), salt (I-691) to salt (I-695),salt (I-698) to salt (I-714), salt (I-719) to salt (I-722), salt (I-723)to salt (I-726), salt (I-729) to salt (I-733), salt (I-736) to salt(I-752), salt (I-757) to salt (I-760), salt (I-761) to salt (I-764),salt (I-767) to salt (I-771), salt (I-774) to salt (I-790), salt (I-795)to salt (I-798), salt (I-799) to salt (I-802), salt (I-805) to salt(I-809), salt (I-812) to salt (I-828), salt (I-833) to salt (I-836),salt (I-837) to salt (I-840), salt (I-843) to salt (I-847), salt (I-850)to salt (I-866), salt (I-871) to salt (I-874), salt (I-875) to salt(I-878), salt (I-881) to salt (I-885), salt (I-888) to salt (I-904),salt (I-909) to salt (I-912), salt (I-913) to salt (I-916), salt (I-919)to salt (I-923), salt (I-926) to salt (1-942), salt (I-947) to salt(I-950), salt (I-951) to salt (I-954), salt (I-957) to salt (I-961),salt (I-964) to salt (I-980), salt (I-985) to salt (I-988), salt (I-989)to salt (1-992), salt (I-995) to salt (I-999), salt (I-1002) to salt(I-1018), salt (I-1023) to salt (I-1026), salt (I-1027) to salt(I-1030), salt (I-1033) to salt (I-1037), salt (I-1040) to salt(I-1056), salt (I-1061) to salt (I-1064), salt (I-1065) to salt(I-1068), salt (I-1071) to salt (I-1075), salt (I-1078) to salt(I-1094), salt (I-1099) to salt (I-1102), salt (I-1103) to salt(I-1106), salt (I-1109) to salt (1-1113), salt (I-1116) to salt(I-1132), salt (I-1137) to salt (I-1140), salt (I-1141) to salt(I-1144), salt (I-1147) to salt (I-1151), salt (I-1154) to salt(1-1170), salt (I-1175) to salt (1-1178), salt (I-1179) to salt(I-1182), salt (I-1185) to salt (I-1189), salt (I-1192) to salt(I-1208), salt (I-1213) to salt (I-1216), salt (I-1217) to salt(I-1220), salt (I-1223) to salt (I-1227), salt (I-1230) to salt(1-1246), salt (I-1251) to salt (I-1254), salt (I-1255) to salt(I-1258), salt (I-1261) to salt (I-1265), salt (I-1268) to salt(I-1284), salt (I-1289) to salt (I-1292), salt (I-1293) to salt(I-1296), salt (I-1299) to salt (I-1303), salt (I-1306) to salt(I-1322), salt (I-1327) to salt (I-1330), salt (I-1331) to salt(I-1334), salt (I-1337) to salt (I-1341), salt (I-1344) to salt(I-1360), salt (I-1365) to salt (1-1368), salt (I-1369) to salt(I-1372), salt (I-1375) to salt (I-1379), salt (I-1382) to salt(I-1398), salt (I-1403) to salt (I-1406), salt (I-1407) to salt(I-1410), salt (I-1413) to salt (I-1417), salt (I-1420) to salt(I-1436), salt (I-1441) to salt (I-1444), salt (I-1445) to salt(I-1448), salt (I-1451) to salt (I-1455), salt (I-1458) to salt(I-1474), salt (I-1479) to salt (I-1482), salt (I-1483) to salt(1-1486), salt (I-1489) to salt (I-1493), salt (I-1496) to salt(I-1512), salt (I-1517) to salt (I-1520), salt (I-1521) to salt(I-1524), salt (I-1527) to salt (I-1531), salt (I-1534) to salt(I-1550), salt (I-1555) to salt (I-1558), salt (I-1559) to salt(I-1562), salt (I-1565) to salt (I-1569), salt (I-1572) to salt(I-1588), salt (I-1593) to salt (I-1596), salt (I-1597) to salt(I-1600), salt (I-1603) to salt (I-1607), salt (I-1610) to salt(I-1626), salt (I-1631) to salt (I-1634), salt (I-1635) to salt(I-1638), salt (I-1641) to salt (I-1645), salt (I-1648) to salt(I-1664), salt (I-1669) to salt (I-1672), salt (I-1673) to salt(1-1676), salt (I-1679) to salt (1-1683), salt (I-1686) to salt(I-1702), salt (I-1707) to salt (I-1710), salt (I-1711) to salt(I-1714), salt (I-1717) to salt (I-1721), salt (I-1724) to salt(I-1740), salt (I-1745) to salt (I-1748), salt (I-1749) to salt(I-1752), salt (I-1755) to salt (I-1759), salt (I-1762) to salt(I-1778), salt (I-1783) to salt (I-1786), salt (I-1787) to salt(I-1790), salt (I-1793) to salt (I-1797), salt (I-1800) to salt(I-1816), salt (I-1821) to salt (I-1824), salt (I-1825) to salt(I-1828), salt (I-1831) to salt (I-1835), salt (I-1838) to salt(I-1854), salt (I-1859) to salt (1-1862), salt (I-1863) to salt(I-1866), salt (I-1869) to salt (I-1873), salt (I-1876) to salt(I-1892), salt (I-1897) to salt (I-1900), salt (I-1901) to salt(I-1904), salt (I-1907) to salt (I-1911), salt (I-1914) to salt(1-1930), salt (I-1935) to salt (1-1938), salt (I-1939) to salt(I-1942), salt (I-1945) to salt (I-1949), salt (I-1952) to salt(I-1968), salt (I-1973) to salt (I-1976), salt (I-1977) to salt(I-1980), salt (I-1983) to salt (I-1987), salt (I-1990) to salt(I-2006), salt (I-2011) to salt (I-2014), salt (I-2015) to salt(I-2018), salt (I-2021) to salt (I-2025), salt (I-2028) to salt(I-2044), salt (I-2049) to salt (I-2052), salt (I-2053) to salt(I-2056), salt (I-2059) to salt (I-2063), salt (I-2066) to salt(I-2082), salt (I-2087) to salt (I-2090), salt (I-2091) to salt(I-2094), salt (I-2097) to salt (I-2101), salt (I-2104) to salt(I-2120), salt (I-2125) to salt (I-2128), salt (I-2129) to salt(I-2132), salt (I-2135) to salt (I-2139), salt (I-2142) to salt(I-2158), salt (I-2163) to salt (I-2166), salt (I-2167) to salt(I-2170), salt (I-2173) to salt (I-2177), salt (I-2180) to salt(I-2196), salt (I-2201) to salt (I-2204), salt (I-2205) to salt(1-2208), salt (I-2211) to salt (1-2215), salt (I-2218) to salt(1-2234), salt (I-2239) to salt (I-2242), salt (I-2243) to salt(I-2246), salt (I-2249) to salt (I-2253), salt (I-2256) to salt(I-2272), salt (I-2277) to salt (I-2280), salt (I-2281) to salt(I-2284), salt (I-2287) to salt (I-2291), salt (I-2294) to salt(I-2310), salt (I-2315) to salt (I-2318), salt (I-2319) to salt(I-2322), salt (I-2325) to salt (I-2329), salt (I-2332) to salt(I-2348), salt (I-2353) to salt (1-2356), salt (I-2357) to salt(I-2360), salt (I-2363) to salt (I-2367), salt (I-2370) to salt(I-2386), salt (I-2391) to salt (I-2394), salt (I-2395) to salt(1-2398), salt (I-2401) to salt (1-2405), salt (I-2408) to salt(I-2424), salt (I-2429) to salt (I-2432), salt (I-2433) to salt(I-2436), salt (I-2439) to salt (I-2443), salt (I-2446) to salt(I-2462), salt (I-2467) to salt (I-2470), salt (I-2471) to salt(I-2474), salt (I-2477) to salt (I-2481), salt (I-2484) to salt(I-2500), salt (I-2505) to salt (I-2508), salt (I-2509) to salt(I-2512), salt (I-2515) to salt (I-2519), salt (I-2522) to salt(I-2538), salt (I-2543) to salt (I-2546), salt (I-2547) to salt(I-2550), salt (I-2553) to salt (I-2557), salt (I-2560) to salt(I-2576), salt (I-2581) to salt (I-2584), salt (I-2585) to salt(I-2588), salt (I-2591) to salt (1-2595), salt (I-2598) to salt(I-2614), salt (I-2619) to salt (I-2622), salt (I-2623) to salt(1-2626), salt (I-2629) to salt (1-2633), salt (I-2636) to salt(I-2652), salt (I-2657) to salt (I-2660), salt (I-2661) to salt(I-2664), salt (I-2667) to salt (I-2671), salt (I-2674) to salt(I-2690), salt (I-2695) to salt (I-2698), salt (I-2699) to salt(1-2702), salt (I-2705) to salt (1-2709), salt (I-2712) to salt(I-2728), salt (I-2733) to salt (I-2736), salt (I-2737) to salt(I-2740), salt (I-2743) to salt (I-2747), salt (I-2750) to salt(I-2766), salt (I-2771) to salt (I-2774), salt (I-2775) to salt(I-2778), salt (I-2781) to salt (I-2785), salt (I-2788) to salt(I-2804), salt (I-2809) to salt (I-2812), salt (I-2813) to salt(I-2816), salt (I-2819) to salt (1-2823), salt (I-2826) to salt(1-2842), salt (I-2847) to salt (I-2850), salt (I-2851) to salt(I-2854), salt (I-2857) to salt (I-2861), salt (I-2864) to salt(1-2880), salt (I-2885) to salt (1-2888), salt (I-2889) to salt(I-2892), salt (I-2895) to salt (I-2899), salt (I-2902) to salt(I-2918), salt (I-2923) to salt (I-2926), salt (I-2927) to salt(I-2930), salt (I-2933) to salt (I-2937), salt (I-2940) to salt(I-2956), salt (I-2961) to salt (I-2964), salt (I-2965) to salt(I-2968), salt (I-2971) to salt (I-2975), salt (I-2978) to salt(I-2994), salt (I-2999) to salt (I-3002) and salt (I-3003) to salt(I-3160).

<Method for Producing Salt (I)>

The salt (I) can be produced by reacting a salt represented by formula(I-a) with a salt represented by formula (I-b) in a solvent:

wherein all symbols are the same as defined above, R^(A), R^(B) andR^(c) each independently represent a hydrocarbon group having 1 to 12carbon atoms, or R^(A), R^(B) and R^(C) may combine together to form anaromatic ring, and R^(D) represents a hydrogen atom or a hydrocarbongroup having 1 to 12 carbon atoms.

Examples of the solvent include chloroform, monochlorobenzene,acetonitrile, water and the like.

The reaction temperature is usually 15° C. to 80° C., and the reactiontime is usually 0.5 to 24 hours.

Examples of the salt represented by formula (I-b) include saltsrepresented by the following formulas. These salts can be easilyproduced by the methods mentioned in JP 2011-116747 A and JP 2016-047815A, or a known production method.

It is possible to produce a salt in which R¹, R² and R³ are*—O-L¹⁰-CO—O—R¹⁰ in the salt (I-a) (salt represented by formula (I-a1))by reacting a salt represented by formula (I-c) with a compoundrepresented by formula (I-d) in the presence of a base catalyst in asolvent:

wherein all symbols are the same as defined above.

Examples of the base include potassium carbonate, potassium iodide,pyridine, triethylamine and the like.

Examples of the solvent include chloroform, monochlorobenzene,dimethylformamide, acetonitrile, ethyl acetate, water and the like.

The reaction temperature is usually 15° C. to 80° C., and the reactiontime is usually 0.5 to 24 hours.

Examples of the compound represented by formula (I-d) include compoundsrepresented by the following formulas, which are easily available on themarket and also can be easily produced by a known production method.

It is possible to produce a salt represented by formula (I-c) byreacting a salt represented by formula (I-e), a compound represented byformula (I-f1), a compound represented by formula (I-f2) and a compoundrepresented by formula (I-f3) in the presence of a catalyst in asolvent:

wherein all symbols are the same as defined above.

Examples of the catalyst include potassium carbonate, sodium hydride andthe like.

Examples of the solvent include chloroform, monochlorobenzene,acetonitrile, water and the like.

The reaction temperature is usually 15° C. to 100° C., and the reactiontime is usually 0.5 to 24 hours.

Examples of the salt represented by formula (I-e) include saltsrepresented by the following formulas, which are easily available on themarket.

Examples of the compound represented by formula (I-f1), the compoundrepresented by formula (I-f2) and the compound represented by formula(I-f3) include compounds represented by the following formulas, whichare easily available on the market.

It is also possible to produce the salt represented by formula (I-c) byreacting a salt represented by formula (I-e), a compound represented byformula (I-f4), a compound represented by formula (I-f5) and a compoundrepresented by formula (I-f6) in the presence of potassium carbonate ina solvent, followed by subjecting to an acid treatment:

wherein all symbols are the same as defined above, and

-   -   R^(ac) represents an acid-labile group.

Examples of the solvent include chloroform, monochlorobenzene,acetonitrile, water and the like.

The reaction temperature is usually 15° C. to 100° C., and the reactiontime is usually 0.5 to 24 hours.

Examples of the acid include p-toluenesulfonic acid, hydrochloric acidand the like.

Examples of the compound represented by formula (I-f4), the compoundrepresented by formula (I-f5) and the compound represented by formula(I-f6) include compounds represented by the following formulas, whichare easily available on the market.

It is possible to produce a salt in which R¹, R² and R³ are *—O—R¹⁰ inthe salt (I-a) (salt represented by formula (I-a2)) by reacting a saltrepresented by formula (I-c) with a compound represented by formula(I-d2) in the presence of a base catalyst in a solvent:

wherein all symbols are the same as defined above.

Examples of the base include sodium hydroxide, potassium hydroxide andthe like.

Examples of the solvent include chloroform, monochlorobenzene,dimethylformamide, acetonitrile, ethyl acetate, water and the like.

The reaction temperature is usually 15° C. to 80° C., and the reactiontime is usually 0.5 to 24 hours.

Examples of the compound represented by formula (I-d2) include compoundsrepresented by the following formulas, which are easily available on themarket and also can be easily produced by a known production method.

It is possible to produce a salt in which R¹, R² and R³ are *—O—CO—O—R¹⁰in the salt (I-a) (salt represented by formula (I-a3)) by reacting asalt represented by formula (I-c) with a compound represented by formula(I-d2) in the presence of carbonyldiimidazole in a solvent:

wherein all symbols are the same as defined above.

Examples of the solvent include chloroform, monochlorobenzene,dimethylformamide, acetonitrile, ethyl acetate, water and the like.

The reaction temperature is usually 15° C. to 80° C., and the reactiontime is usually 0.5 to 24 hours.

<Acid Generator>

The acid generator of the present invention is an acid generatorcomprising a salt (I). The acid generator may comprise the salt (I)alone, or two or more of the salts (I).

The acid generator of the present invention may comprise, in addition tothe salt (I), an acid generator known in the resist field (hereinaftersometimes referred to as “acid generator (B)”). The acid generator (B)may be used alone, or two or more acid generators may be used incombination.

Either nonionic or ionic acid generator may be used as the acidgenerator (B). Examples of the nonionic acid generator include sulfonateesters (e.g., 2-nitrobenzyl ester, aromatic sulfonate, oxime sulfonate,N-sulfonyloxyimide, sulfonyloxyketone, diazonaphthoquinone 4-sulfonate),sulfones (e.g., disulfone, ketosulfone, sulfonyldiazomethane) and thelike. Typical examples of the ionic acid generator include onium saltscontaining an onium cation (e.g., diazonium salt, phosphonium salt,sulfonium salt, iodonium salt). Examples of the anion of the onium saltinclude sulfonic acid anion, sulfonylimide anion, sulfonylmethide anionand the like.

Specific examples of the acid generator (B) include compounds generatingan acid upon exposure to radiation mentioned in JP 63-26653 A, JP55-164824 A, JP 62-69263 A, JP 63-146038 A, JP 63-163452 A, JP 62-153853A, JP 63-146029 A, U.S. Pat. Nos. 3,779,778, 3,849,137, DE Patent No.3914407 and EP Patent No. 126,712. Compounds produced by a known methodmay also be used. Two or more acid generators (B) may also be used incombination.

The acid generator (B) is preferably a salt represented by formula (B1)(hereinafter sometimes referred to as “acid generator (B1)”, in whichthe salt (I) is excluded):

wherein, in formula (B1),

-   -   Q^(b1) and Q^(b2) each independently represent a hydrogen atom,        a fluorine atom, an alkyl group having 1 to 6 carbon atoms or a        perfluoroalkyl group having 1 to 6 carbon atoms,    -   L^(b1) represents a divalent saturated hydrocarbon group having        1 to 24 carbon atoms, —CH₂— included in the divalent saturated        hydrocarbon group may be replaced by —O— or —CO—, and a hydrogen        atom included in the divalent saturated hydrocarbon group may be        substituted with a fluorine atom or a hydroxy group,    -   Y represents a methyl group which may have a substituent, or an        alicyclic hydrocarbon group having 3 to 24 carbon atoms which        may have a substituent, and —CH₂— included in the alicyclic        hydrocarbon group may be replaced by —O—, —S—, —SO₂— or —CO—,        and    -   Z1+ represents an organic cation.

Examples of Q^(b1), Q^(b2), L^(b1) and Y in formula (B1) include thosewhich are the same as the above-mentioned Q¹, Q², L¹ and Y¹ in formula(I-A).

Examples of the sulfonic acid anion in formula (B1) include those whichare the same as the anion represented by formula (I-A).

Examples of the organic cation as for Z1+ include an organic oniumcation, an organic sulfonium cation, an organic iodonium cation, anorganic ammonium cation, a benzothiazolium cation and an organicphosphonium cation. Of these, an organic sulfonium cation and an organiciodonium cation are preferable, and an arylsulfonium cation is morepreferable. Specific examples thereof include a cation represented byany one of formula (b2-1) to formula (b2-4) (hereinafter sometimesreferred to as “cation (b2-1)” or the like according to the number offormula).

In formula (b2-1) to formula (b2-4),

-   -   R^(b4) to R^(b6) each independently represent a chain        hydrocarbon group having 1 to 30 carbon atoms, an alicyclic        hydrocarbon group having 3 to 36 carbon atoms or an aromatic        hydrocarbon group having 6 to 36 carbon atoms, a hydrogen atom        included in the chain hydrocarbon group may be substituted with        a hydroxy group, an alkoxy group having 1 to 12 carbon atoms, an        alicyclic hydrocarbon group having 3 to 12 carbon atoms or an        aromatic hydrocarbon group having 6 to 18 carbon atoms, a        hydrogen atom included in the alicyclic hydrocarbon group may be        substituted with a halogen atom, an aliphatic hydrocarbon group        having 1 to 18 carbon atoms, an alkylcarbonyl group having 2 to        4 carbon atoms or a glycidyloxy group, and a hydrogen atom        included in the aromatic hydrocarbon group may be substituted        with a halogen atom, a hydroxy group, an aliphatic hydrocarbon        group having 1 to 18 carbon atoms, an alkyl fluoride group        having 1 to 12 carbon atoms or an alkoxy group having 1 to 12        carbon atoms.

R^(b4) and R^(b5) may be bonded to each other to form a ring togetherwith sulfur atoms to which R^(b4) and R^(b5) are bonded, and —CH₂—included in the ring may be replaced by —O—, —S— or —CO—,

-   -   R^(b7) and R^(b8) each independently represent a halogen atom, a        hydroxy group, an aliphatic hydrocarbon group having 1 to 12        carbon atoms, an alkyl fluoride group having 1 to 12 carbon        atoms or an alkoxy group having 1 to 12 carbon atoms,    -   m2 and n2 each independently represent an integer of 0 to 5,    -   when m2 is 2 or more, a plurality of R^(b7) may be the same or        different, and when n2 is 2 or more, a plurality of R^(b8) may        be the same or different,    -   R^(b9) and R^(b10) each independently represent a chain        hydrocarbon group having 1 to 36 carbon atoms or an alicyclic        hydrocarbon group having 3 to 36 carbon atoms,    -   R^(b9) and R^(b10) may be bonded to each other to form a ring        together with sulfur atoms to which R^(b9) and R^(b10) are        bonded, and —CH₂— included in the ring may be replaced by —O—,        —S— or —CO—,    -   R^(b11) represents a hydrogen atom, a chain hydrocarbon group        having 1 to 36 carbon atoms, an alicyclic hydrocarbon group        having 3 to 36 carbon atoms or an aromatic hydrocarbon group        having 6 to 18 carbon atoms,    -   R^(b12) represents a chain hydrocarbon group having 1 to 12        carbon atoms, an alicyclic hydrocarbon group having 3 to 18        carbon atoms or an aromatic hydrocarbon group having 6 to 18        carbon atoms, a hydrogen atom included in the chain hydrocarbon        group may be substituted with an aromatic hydrocarbon group        having 6 to 18 carbon atoms, a hydrogen atom included in the        aromatic hydrocarbon group may be substituted with an alkoxy        group having 1 to 12 carbon atoms or an alkylcarbonyloxy group        having 1 to 12 carbon atoms,    -   R^(b11) and R^(b12) may be bonded to each other to form a ring,        including —CH—CO— to which R^(b11) and R^(b12) are bonded, and        —CH₂— included in the ring may be replaced by —O—, —S— or —CO—,    -   R^(b13) to R^(b18) each independently represent a halogen atom,        a hydroxy group, an aliphatic hydrocarbon group having 1 to 12        carbon atoms, an alkyl fluoride group having 1 to 12 carbon        atoms or an alkoxy group having 1 to 12 carbon atoms,    -   R^(b13) and R^(b14) may be bonded to each other to form a ring        having a sulfur atom together with the benzene ring to which        R^(b13) and R^(b14) are bonded, and —CH₂— included in the ring        may be replaced by —O—, —S— or —CO—,    -   L^(b31) represents a sulfur atom or an oxygen atom,    -   o2, p2, s2 and t2 each independently represent an integer of 0        to 5,    -   q2 and r2 each independently represent an integer of 0 to 4,    -   u2 represents 0 or 1, and    -   when o2 is 2 or more, a plurality of R^(b13) are the same or        different, when p2 is 2 or more, a plurality of R^(b14) are the        same or different, when q2 is 2 or more, a plurality of R^(b15)        are the same or different, when r2 is 2 or more, a plurality of        R^(b16) are the same or different, when s2 is 2 or more, a        plurality of R^(b17) are the same or different, and when t2 is 2        or more, a plurality of R^(b18) are the same or different.

When u2 is 0, any one of o2, p2, q2 and r2 is preferably 1 or more andat least one of R^(b13) to R^(b16) is preferably a halogen atom, andwhen u2 is 1, any one of o2, p2, s2, t2, q2 and r2 is preferably 1 ormore and at least one of R^(b13) to R^(b18) is preferably a halogenatom.

Further, when u2 is 0, r2 is preferably 1 or more, and morepreferably 1. When u2 is 0 and r2 is 1 or more, R^(b16) is preferably ahalogen atom.

The aliphatic hydrocarbon group represents a chain hydrocarbon group andan alicyclic hydrocarbon group.

Examples of the chain hydrocarbon group include alkyl groups such as amethyl group, an ethyl group, a propyl group, an isopropyl group, abutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, ahexyl group, an octyl group and a 2-ethylhexyl group.

Particularly, the chain hydrocarbon group of R^(b9) to R^(b12)preferably has 1 to 12 carbon atoms.

The alicyclic hydrocarbon group may be either monocyclic or polycyclic,and examples of the monocyclic alicyclic hydrocarbon group includecycloalkyl groups such as a cyclopropyl group, a cyclobutyl group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup and a cyclodecyl group. Examples of the polycyclic alicyclichydrocarbon group include a decahydronaphthyl group, an adamantyl group,a norbornyl group and the following groups.

Particularly, the alicyclic hydrocarbon group of R^(b9) to R^(b12)preferably has 3 to 18 carbon atoms, and more preferably 4 to 12 carbonatoms.

Examples of the alicyclic hydrocarbon group in which a hydrogen atom issubstituted with an aliphatic hydrocarbon group include amethylcyclohexyl group, a dimethylcyclohexyl group, a2-methyladamantan-2-yl group, a 2-ethyladamantan-2-yl group, a2-isopropyladamantan-2-yl group, a methylnorbornyl group, an isobornylgroup and the like. In the alicyclic hydrocarbon group in which ahydrogen atom is substituted with an aliphatic hydrocarbon group, thetotal number of carbon atoms of the alicyclic hydrocarbon group and thealiphatic hydrocarbon group is preferably 20 or less.

The alkyl fluoride group represents an alkyl group having 1 to 12 carbonatoms which has a fluorine atom, and examples thereof include afluoromethyl group, a difluoromethyl group, a trifluoromethyl group, aperfluorobutyl and the like. The number of carbon atoms of the alkylfluoride group is preferably 1 to 9, more preferably 1 to 6, still morepreferably 1 to 4.

Examples of the aromatic hydrocarbon group include aryl groups such as aphenyl group, a biphenyl group, a naphthyl group and a phenanthrylgroup. The aromatic hydrocarbon group may have a chain hydrocarbon groupor an alicyclic hydrocarbon group, and it is possible to exemplifyaromatic hydrocarbon groups which have a chain hydrocarbon group having1 to 18 carbon atoms (a tolyl group, a xylyl group, a cumenyl group, amesityl group, a p-ethylphenyl group, a p-tert-butylphenyl group, a2,6-diethylphenyl group, a 2-methyl-6-ethylphenyl group, etc.) andaromatic hydrocarbon groups which have an alicyclic hydrocarbon grouphaving 3 to 18 carbon atoms (a p-cyclohexylphenyl group, ap-adamantylphenyl group, etc.) and the like. When the aromatichydrocarbon group has a chain hydrocarbon group or an alicyclichydrocarbon group, a chain hydrocarbon group having 1 to 18 carbon atomsand an alicyclic hydrocarbon group having 3 to 18 carbon atoms arepreferable.

Examples of the aromatic hydrocarbon group in which a hydrogen atom issubstituted with an alkoxy group include a p-methoxyphenyl group and thelike.

Examples of the chain hydrocarbon group in which a hydrogen atom issubstituted with an aromatic hydrocarbon group include aralkyl groupssuch as a benzyl group, a phenethyl group, a phenylpropyl group, atrityl group, a naphthylmethyl group and a naphthylethyl group.

Examples of the alkoxy group include a methoxy group, an ethoxy group, apropoxy group, a butoxy group, a pentyloxy group, a hexyloxy group, aheptyloxy group, an octyloxy group, a decyloxy group and a dodecyloxygroup.

Examples of the alkylcarbonyl group include an acetyl group, a propionylgroup and a butyryl group.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom.

Examples of the alkylcarbonyloxy group include a methylcarbonyloxygroup, an ethylcarbonyloxy group, a propylcarbonyloxy group, anisopropylcarbonyloxy group, a butylcarbonyloxy group, asec-butylcarbonyloxy group, a tert-butylcarbonyloxy group, apentylcarbonyloxy group, a hexylcarbonyloxy group, an octylcarbonyloxygroup and a 2-ethylhexylcarbonyloxy group.

The ring formed by bonding R^(b4) and R^(b5) each other, together withsulfur atoms to which R^(b4) and R^(b5) are bonded, may be a monocyclic,polycyclic, aromatic, nonaromatic, saturated or unsaturated ring. Thisring includes a ring having 3 to 18 carbon atoms and is preferably aring having 4 to 18 carbon atoms. The ring having a sulfur atom includesa 3-membered to 12-membered ring and is preferably a 3-membered to7-membered ring and includes, for example, the following rings and thelike. * represents a bonding site.

The ring formed by combining R^(b9) and R^(b10) together may be amonocyclic, polycyclic, aromatic, nonaromatic, saturated or unsaturatedring. This ring includes a 3-membered to 12-membered ring and ispreferably a 3-membered to 7-membered ring. The ring includes, forexample, a thiolan-1-ium ring (tetrahydrothiophenium ring), athian-1-ium ring, a 1,4-oxathian-4-ium ring and the like.

The ring formed by combining R^(b11) and R^(b12) together may be amonocyclic, polycyclic, aromatic, nonaromatic, saturated or unsaturatedring. This ring includes a 3-membered to 12-membered ring and ispreferably a 3-membered to 7-membered ring. Examples thereof include anoxocycloheptane ring, an oxocyclohexane ring, an oxonorbornane ring, anoxoadamantane ring and the like.

Of cation (b2-1) to cation (b2-4), a cation (b2-1) is preferable.

Examples of the cation (b2-1) include the following cations.

Examples of the cation (b2-2) include the following cations.

Examples of the cation (b2-3) include the following cations.

Examples of the cation (b2-4) include the following cations.

The acid generator (B) is a combination of the anion mentioned above andthe organic cation mentioned above, and these can be optionallycombined. The acid generator (B) preferably includes a combination of ananion represented by any one of formula (I-a-1) to formula (I-a-3),formula (I-a-7) to formula (I-a-19) and formula (I-a-22) to formula(I-a-40) with a cation (b2-1), a cation (b2-2), a cation (b2-3) or acation (b2-4).

The acid generator (B) preferably includes those represented by formula(B1-1) to formula (B1-60). Of these acid generators, those containing anarylsulfonium cation are preferable and those represented by formula(B1-1) to formula (B1-3), formula (B1-5) to formula (B1-7), formula(B1-11) to formula (B1-14), formula (B1-20) to formula (B1-26), formula(B1-29) and formula (B1-31) to formula (B1-60) are particularlypreferable.

When the salt (I) and the acid generator (B) are included as the acidgenerator, a ratio of the content of the salt (I) to that of the acidgenerator (B) (mass ratio; salt (I):acid generator (B)) is usually 1:99to 99:1, preferably 2:98 to 98:2, more preferably 5:95 to 95:5, stillmore preferably 10:90 to 90:10, and particularly preferably 15:85 to85:15.

<Resist Composition>

The resist composition of the present invention comprises an acidgenerator comprising a salt (I) and a resin having an acid-labile group(hereinafter sometimes referred to as “resin (A)”). The “acid-labilegroup” means a group having a leaving group which is eliminated bycontact with an acid, thus converting a constitutional unit into aconstitutional unit having a hydrophilic group (e.g. a hydroxy group ora carboxy group).

The resist composition of the present invention preferably comprises aquencher such as a salt generating an acid having an acidity lower thanthat of an acid generated from the acid generator (hereinafter sometimesreferred to as “quencher (C)”), and preferably comprises a solvent(hereinafter sometimes referred to as “solvent (E)”).

<Acid Generator>

In the resist composition of the present invention, the total content ofthe acid generator is preferably 1 part by mass or more and 45 parts bymass or less, more preferably 1 part by mass or more and 40 parts bymass or less, and still more preferably 3 parts by mass or more and 40parts by mass or less, based on 100 parts by mass of the below-mentionedresin (A).

<Resin (A)>

The resin (A) includes a structural unit having an acid-labile group(hereinafter sometimes referred to as “structural unit (a1)”). It ispreferable that the resin (A) further includes a structural unit otherthan the structural unit (a1). Examples of the structural unit otherthan the structural unit (a1) include a structural unit having noacid-labile group (hereinafter sometimes referred to as “structural unit(s)”), a structural unit other than the structural unit (a1) and thestructural unit (s) (e.g. a structural unit having a halogen atommentioned later (hereinafter sometimes referred to as “structural unit(a4)”), a structural unit having a non-leaving hydrocarbon groupmentioned later (hereinafter sometimes referred to as “structural unit(a5)”) and other structural units derived from monomers known in theart.

<Structural Unit (a1)>

The structural unit (a1) is derived from a monomer having an acid-labilegroup (hereinafter sometimes referred to as “monomer (a1)”).

The acid-labile group contained in the resin (A) is preferably a grouprepresented by formula (1) (hereinafter also referred to as group (1))and/or a group represented by formula (2) (hereinafter also referred toas group (2)):

wherein, in formula (1), R^(a1), R^(a2) and R^(a3) each independentlyrepresent an alkyl group having 1 to 8 carbon atoms, an alkenyl grouphaving 2 to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to20 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbonatoms, or a group obtained by combining these groups, or R^(a1) andR^(a2) are bonded to each other to form an alicyclic hydrocarbon grouphaving 3 to 20 carbon atoms together with carbon atoms to which R^(a1)and R^(a2) are bonded,

-   -   ma and na each independently represent 0 or 1, and at least one        of ma and na represents 1, and    -   represents a bonding site:

wherein, in formula (2), R^(a1′) and R^(a2′) each independentlyrepresent a hydrogen atom or a hydrocarbon group having 1 to 12 carbonatoms, R^(a3′) represents a hydrocarbon group having 1 to 20 carbonatoms, or R^(a2′) and R^(a3′) are bonded to each other to form aheterocyclic ring group having 3 to 20 carbon atoms together with carbonatoms and X to which R^(a2′) and R^(a3′) are bonded, and —CH₂— includedin the hydrocarbon group and the heterocyclic ring group may be replacedby —O— or —S—,

-   -   X represents an oxygen atom or a sulfur atom,    -   na′ represents 0 or 1, and    -   represents a bonding site.

Examples of the alkyl group in R^(a1), R^(a2) and R^(a3) include amethyl group, an ethyl group, a propyl group, a butyl group, a pentylgroup, a hexyl group, a heptyl group, an octyl group and the like.

Examples of the alkenyl group in R^(a1), R^(a2) and R^(a3) include anethenyl group, a propenyl group, an isopropenyl group, a butenyl group,an isobutenyl group, a tert-butenyl group, a pentenyl group, a hexenylgroup, a heptenyl group, an octenyl group, an isooctenyl group and anonenyl group.

The alicyclic hydrocarbon group in R^(a1), R^(a2) and R^(a3) may beeither monocyclic or polycyclic. Examples of the monocyclic alicyclichydrocarbon group include cycloalkyl groups such as a cyclopentyl group,a cyclohexyl group, a cycloheptyl group and a cyclooctyl group. Examplesof the polycyclic alicyclic hydrocarbon group include adecahydronaphthyl group, an adamantyl group, a norbornyl group and thefollowing groups (* represents a bonding site). The number of carbonatoms of the alicyclic hydrocarbon group of R^(a1), R^(a2) and R^(a3) ispreferably 3 to 16.

Examples of the aromatic hydrocarbon group in R^(a1), R^(a2) and R^(a3)include aryl groups such as a phenyl group, a naphthyl group, an anthrylgroup, a biphenyl group and a phenanthryl group.

Examples of the combined group include groups obtained by combining theabove-mentioned alkyl group and alicyclic hydrocarbon group (e.g.,alkylcycloalkyl groups or cycloalkylalkyl groups, such as amethylcyclohexyl group, a dimethylcyclohexyl group, a methylnorbornylgroup, a cyclohexylmethyl group, an adamantylmethyl group, anadamantyldimethyl group and a norbornylethyl group), aralkyl groups suchas a benzyl group, aromatic hydrocarbon groups having an alkyl group (ap-methylphenyl group, a p-tert-butylphenyl group, a tolyl group, a xylylgroup, a cumenyl group, a mesityl group, a 2,6-diethylphenyl group, a2-methyl-6-ethylphenyl group, etc.), aromatic hydrocarbon groups havingan alicyclic hydrocarbon group (a p-cyclohexylphenyl group, ap-adamantylphenyl group, etc.), aryl-cycloalkyl groups such as aphenylcyclohexyl group, and the like.

Preferably, ma is 0 and na is 1.

When R^(a1) and R^(a2) are bonded to each other to form an alicyclichydrocarbon group, examples of —C(R^(a1)) (R^(a2)) (R^(a3)) include thefollowing groups. The alicyclic hydrocarbon group preferably has 3 to 12carbon atoms. * represents a bonding site to —O—.

Examples of the hydrocarbon group in R^(a1′), R^(a2′) and R^(a3′)include an alkyl group, an alicyclic hydrocarbon group, an aromatichydrocarbon group, and groups formed by combining these groups.

Examples of the alkyl group and the alicyclic hydrocarbon group includethose which are the same as mentioned in R^(a1), R^(a2) and R^(a3).

Examples of the aromatic hydrocarbon group include aryl groups such as aphenyl group, a naphthyl group, an anthryl group, a biphenyl group and aphenanthryl group.

Examples of the combined group include groups obtained by combining theabove-mentioned alkyl group and alicyclic hydrocarbon group (e.g.,alkylcycloalkyl groups or cycloalkylalkyl groups, such as amethylcyclohexyl group, a dimethylcyclohexyl group, a methylnorbornylgroup, a cyclohexylmethyl group, an adamantylmethyl group, anadamantyldimethyl group and a norbornylethyl group), aralkyl groups suchas a benzyl group, aromatic hydrocarbon groups having an alkyl group (ap-methylphenyl group, a p-tert-butylphenyl group, a tolyl group, a xylylgroup, a cumenyl group, a mesityl group, a 2,6-diethylphenyl group, a2-methyl-6-ethylphenyl group, etc.), aromatic hydrocarbon groups havingan alicyclic hydrocarbon group (a p-cyclohexylphenyl group, ap-adamantylphenyl group, etc.), aryl-cycloalkyl groups such as aphenylcyclohexyl group, and the like.

When R^(a2′) and R^(a3′) are bonded to each other to form a heterocyclicring group together with carbon atoms and X to which R^(a2′) and R^(a3′)are bonded, examples of —C(R^(a1′)) (R^(a2′))—X—R^(a3′) include thefollowing groups. * represents a bonding site.

At least one of R^(a1′) and R^(a2′) is preferably a hydrogen atom.

na′ is preferably 0.

Examples of the group (1) include the following groups.

A group wherein, in formula (1), R^(a1), R^(a2) and R^(a3) are alkylgroups, ma=0 and na=1. The group is preferably a tert-butoxycarbonylgroup.

A group wherein, in formula (1), R^(a1) and R^(a2) are bonded to eachother to form an adamantyl group together with carbon atoms to whichR^(a1) and R^(a2) are bonded, R^(a3) is an alkyl group, ma=0 and na=1.

A group wherein, in formula (1), R^(a1) and R^(a2) are eachindependently an alkyl group, R^(a3) is an adamantyl group, ma=0 andna=1.

Specific examples of the group (1) include the following groups. *represents a bonding site.

Specific examples of the group (2) include the following groups. *represents a bonding site.

The monomer (a1) is preferably a monomer having an acid-labile group andan ethylenic unsaturated bond, and more preferably a (meth)acrylicmonomer having an acid-labile group.

Of the (meth)acrylic monomers having an acid-labile group, those havingan alicyclic hydrocarbon group having 5 to 20 carbon atoms arepreferably exemplified. When a resin (A) including a structural unitderived from a monomer (a1) having a bulky structure such as analicyclic hydrocarbon group is used in a resist composition, it ispossible to improve the resolution of a resist pattern.

The structural unit derived from a (meth)acrylic monomer having a group(1) preferably includes a structural unit represented by formula (a1-0)(hereinafter sometimes referred to as structural unit (a1-0)), astructural unit represented by formula (a1-1) (hereinafter sometimesreferred to as structural unit (a1-1)) or a structural unit representedby formula (a1-2) (hereinafter sometimes referred to as structural unit(a1-2)). More preferably, the structural unit is at least one structuralunit selected from the group consisting of structural unit (a1-0),structural unit (a1-1) and structural unit (a1-2), and still morepreferably at least one structural unit selected from the groupconsisting of structural unit (a1-1) and structural unit (a1-2). Thesestructural units may be used alone, or two or more structural units maybe used in combination.

In formula (a1-0), formula (a1-1) and formula (a1-2),

-   -   L^(a01), L^(a1) and L^(a2) each independently represent —O— or        *—O—(CH₂)_(k1)—CO—O—, k1 represents an integer of 1 to 7, and *        represents a bonding site to —CO—,    -   R^(a01), R^(a4) and R^(a5) each independently represent a        hydrogen atom, a halogen atom or an alkyl group having 1 to 6        carbon atoms which may have a halogen atom,    -   R^(a02), R^(a03) and R^(a04) each independently represent an        alkyl group having 1 to 8 carbon atoms, an alicyclic hydrocarbon        group having 3 to 18 carbon atoms, an aromatic hydrocarbon group        having 6 to 18 carbon atoms, or a group obtained by combining        these groups,    -   R^(a6) and R^(a7) each independently represent an alkyl group        having 1 to 8 carbon atoms, an alkenyl group having 2 to 8        carbon atoms, an alicyclic hydrocarbon group having 3 to 18        carbon atoms, an aromatic hydrocarbon group having 6 to 18        carbon atoms, or a group obtained by combining these groups,    -   m1 represents an integer of 0 to 14,    -   n1 represents an integer of 0 to 10, and    -   n1′ represents an integer of 0 to 3.

R^(a01), R^(a4) and R^(a5) are preferably a hydrogen atom or a methylgroup, and more preferably a methyl group.

L^(a01), L^(a1) and L^(a2) are preferably an oxygen atom or*—O—(CH₂)_(k01)—CO—O— (in which k01 is preferably an integer of 1 to 4,and more preferably 1), and more preferably an oxygen atom.

Examples of the alkyl group, the alkenyl group, the alicyclichydrocarbon group, the aromatic hydrocarbon group, and groups obtainedby combining these groups in R^(a02), R^(a03), R^(a04), R^(a6) andR^(a7) include the same groups as mentioned as for R^(a1), R^(a2) andR^(a3) of formula (1).

The alkyl group in R^(a02), R^(a03) and R^(a04) is preferably an alkylgroup having 1 to 6 carbon atoms, more preferably a methyl group or anethyl group, and still more preferably a methyl group.

The alkyl group in R^(a6) and R^(a7) is preferably an alkyl group having1 to 6 carbon atoms, more preferably a methyl group, an ethyl group, anisopropyl group or a t-butyl group, and still more preferably an ethylgroup, an isopropyl group or a t-butyl group.

The alkenyl group in R^(a6) and R^(a7) is preferably an alkenyl grouphaving 2 to 6 carbon atoms, and more preferably an ethenyl group, apropenyl group, an isopropenyl group or a butenyl group.

The number of carbon atoms of the alicyclic hydrocarbon group as forR^(a02), R^(a03), R^(a04), R^(a6) and R^(a7) is preferably 5 to 12, andmore preferably 5 to 10.

The number of carbon atoms of the aromatic hydrocarbon group of R^(a02),R^(a03), R^(a04), R^(a6) and R^(a7) is preferably 6 to 12, and morepreferably 6 to 10.

The total number of carbon atoms of the group obtained by combining thealkyl group with the alicyclic hydrocarbon group is preferably 18 orless.

The total number of carbon atoms of the group obtained by combining thealkyl group with the aromatic hydrocarbon group is preferably 18 orless.

R^(a02) and R^(a03) are preferably an alkyl group having 1 to 6 carbonatoms or an aromatic hydrocarbon group having 6 to 12 carbon atoms, andmore preferably a methyl group, an ethyl group, a phenyl group or anaphthyl group.

R^(a04) is preferably an alkyl group having 1 to 6 carbon atoms or analicyclic hydrocarbon group having 5 to 12 carbon atoms, and morepreferably a methyl group, an ethyl group, a cyclohexyl group or anadamantyl group.

R^(a6) and R^(a7) are preferably an alkyl group having 1 to 6 carbonatoms, an alkenyl group having 2 to 6 carbon atoms or an aromatichydrocarbon group having 6 to 12 carbon atoms, more preferably a methylgroup, an ethyl group, an isopropyl group, a t-butyl group, an ethenylgroup, a phenyl group or a naphthyl group, and still more preferably anethyl group, an isopropyl group, a t-butyl group, an ethenyl group or aphenyl group.

m1 is preferably an integer of 0 to 3, and more preferably 0 or 1.

n1 is preferably an integer of 0 to 3, and more preferably 0 or 1.

n1′ is preferably 0 or 1.

The structural unit (a1-0) includes, for example, a structural unitrepresented by any one of formula (a1-0-1) to formula (a1-0-18) and astructural unit in which a methyl group corresponding to R^(a01) in thestructural unit (a1-0) is substituted with a hydrogen atom, a halogenatom, a haloalkyl group (alkyl group having a halogen atom) or otheralkyl groups, and is preferably a structural unit represented by any oneof formula (a1-0-1) to formula (a1-0-10), formula (a1-0-13) and formula(a1-0-14).

The structural unit (a1-1) includes, for example, structural unitsderived from the monomers mentioned in JP 2010-204646 A. Of thesestructural units, a structural unit represented by any one of formula(a1-1-1) to formula (a1-1-7) and a structural unit in which a methylgroup corresponding to R^(a4) in the structural unit (a1-1) issubstituted with a hydrogen atom, a halogen atom, a haloalkyl group orother alkyl groups are preferable, and a structural unit represented byany one of formula (a1-1-1) to formula (a1-1-4) is more preferable.

Examples of the structural unit (a1-2) include a structural unitrepresented by any one of formula (a1-2-1) to formula (a1-2-14), and astructural unit in which a methyl group corresponding to R^(a5) in thestructural unit (a1-2) is substituted with a hydrogen atom, a halogenatom, a haloalkyl group or other alkyl groups, and a structure unitrepresented by any one of formula (a1-2-2), formula (a1-2-5), formula(a1-2-6) and formula (a1-2-10) to formula (a1-2-14) is preferable.

When the resin (A) includes a structural unit (a1-0) and/or a structuralunit (a1-1) and/or a structural unit (a1-2), the total content thereofis usually 10 to 95 mol %, preferably 15 to 90 mol %, more preferably 20to 85 mol %, still more preferably 25 to 70 mol %, and yet morepreferably 30 to 70 mol %, based on all structural units of the resin(A).

In the structural unit (a1), examples of the structural unit having agroup (2) include a structural unit represented by formula (a1-4)(hereinafter sometimes referred to as “structural unit (a1-4)”):

wherein, in formula (a1-4),

-   -   R^(a32) represents a hydrogen atom, a halogen atom, or an alkyl        group having 1 to 6 carbon atoms which may have a halogen atom,    -   R^(a33) represents a halogen atom, a hydroxy group, an alkyl        group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6        carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms,        an alkoxyalkoxy group having 2 to 12 carbon atoms, an        alkylcarbonyl group having 2 to 4 carbon atoms, an        alkylcarbonyloxy group having 2 to 4 carbon atoms, an        acryloyloxy group or a methacryloyloxy group,    -   A^(a30) represents a single bond or        *—X^(a3)1-(A^(a32)-X^(a32))_(nc)— and * represents a bonding        site to carbon atoms to which —R^(a32) is bonded,    -   A^(a32) represents an alkanediyl group having 1 to 6 carbon        atoms,    -   X^(a31) and X^(a32) each independently represent —O—, —CO—O— or        —O—CO—,    -   nc represents 0 or 1,    -   la represents an integer of 0 to 4, and when la is an integer of        2 or more, a plurality of R^(a33) may be the same or different        from each other, and    -   R^(a34) and R^(a35) each independently represent a hydrogen atom        or a hydrocarbon group having 1 to 12 carbon atoms, R^(a36)        represents a hydrocarbon group having 1 to 20 carbon atoms, or        R^(a35) and R^(a36) are bonded to each other to form a divalent        hydrocarbon group having 2 to 20 carbon atoms together with        —C—O— to which R^(a35) and R^(a36) are bonded, and —CH₂—        included in the hydrocarbon group and the divalent hydrocarbon        group may be replaced by —O— or —S—.

Examples of the halogen atom in R^(a32) and R^(a33) include a fluorineatom, a chlorine atom and a bromine atom.

Examples of the alkyl group having 1 to 6 carbon atoms which may have ahalogen atom in R^(a32) include a trifluoromethyl group, adifluoromethyl group, a methyl group, a perfluoroethyl group, a2,2,2-trifluoroethyl group, a 1,1,2,2-tetrafluoroethyl group, an ethylgroup, a perfluoropropyl group, a 2,2,3,3,3-pentafluoropropyl group, apropyl group, a perfluorobutyl group, a 1,1,2,2,3,3,4,4-octafluorobutylgroup, a butyl group, a perfluoropentyl group, a2,2,3,3,4,4,5,5,5-nonafluoropentyl group, a pentyl group, a hexyl groupand a perfluorohexyl group.

R^(a32) is preferably a hydrogen atom or an alkyl group having 1 to 4carbon atoms, more preferably a hydrogen atom, a methyl group or anethyl group, and still more preferably a hydrogen atom or a methylgroup.

Examples of the alkyl group in R^(a33) include a methyl group, an ethylgroup, a propyl group, an isopropyl group, a butyl group, a sec-butylgroup, a tert-butyl group, a pentyl group and a hexyl group. The alkylgroup is preferably an alkyl group having 1 to 4 carbon atoms, morepreferably a methyl group or an ethyl group, and still more preferably amethyl group.

Examples of the alkoxy group in R^(a33) include a methoxy group, anethoxy group, a propoxy group, an isopropoxy group, a butoxy group, asec-butoxy group, a tert-butoxy group, a pentyloxy group and a hexyloxygroup. The alkoxy group is preferably an alkoxy group having 1 to 4carbon atoms, more preferably a methoxy group or an ethoxy group, andstill more preferably a methoxy group.

Examples of the alkoxyalkyl group in R^(a33) include a methoxymethylgroup, an ethoxyethyl group, a propoxymethyl group, an isopropoxymethylgroup, a butoxymethyl group, a sec-butoxymethyl group and atert-butoxymethyl group. The alkoxyalkyl group is preferably analkoxyalkyl group having 2 to 8 carbon atoms, more preferably amethoxymethyl group or an ethoxyethyl group, and still more preferably amethoxymethyl group.

Examples of the alkoxyalkoxy group in R^(a33) include a methoxymethoxygroup, a methoxyethoxy group, an ethoxymethoxy group, an ethoxyethoxygroup, a propoxymethoxy group, an isopropoxymethoxy group, abutoxymethoxy group, a sec-butoxymethoxy group and a tert-butoxymethoxygroup. The alkoxyalkoxy group is preferably an alkoxyalkoxy group having2 to 8 carbon atoms, and more preferably a methoxyethoxy group or anethoxyethoxy group.

Examples of the alkylcarbonyl group in R^(a33) include an acetyl group,a propionyl group and a butyryl group. The alkylcarbonyl group ispreferably an alkylcarbonyl group having 2 to 3 carbon atoms, and morepreferably an acetyl group.

Examples of the alkylcarbonyloxy group in R^(a33) include an acetyloxygroup, a propionyloxy group and a butyryloxy group. The alkylcarbonyloxygroup is preferably an alkylcarbonyloxy group having 2 to 3 carbonatoms, and more preferably an acetyloxy group.

R^(a33) is preferably a halogen atom, a hydroxy group, an alkyl grouphaving 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atomsor an alkoxyalkoxy group having 2 to 8 carbon atoms, more preferably afluorine atom, an iodine atom, a hydroxy group, a methyl group, amethoxy group, an ethoxy group, an ethoxyethoxy group or anethoxymethoxy group, and still more preferably a fluorine atom, aniodine atom, a hydroxy group, a methyl group, a methoxy group or anethoxyethoxy group.

Examples of the *—X^(a3)1-(A^(a32)-X^(a32))_(n)— include *—O—, *—CO—O—,*—O—CO—, *—CO—O-A^(a32)-CO—O—, *—O—CO-A^(a32)-O—, *—O-A^(a32)-CO—O—,*—CO—O-A^(a32)-O—CO— and *—O—CO-A^(a32)-O—CO. Of these, *—CO—O—,*—CO—O-A^(a32)-CO—O— or *—O-A^(a32)-CO—O— is preferable.

Examples of the alkanediyl group in A^(a32) include a methylene group,an ethylene group, a propane-1,3-diyl group, a propane-1,2-diyl group, abutane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diylgroup, a butane-1,3-diyl group, a 2-methylpropane-1,3-diyl group, a2-methylpropane-1,2-diyl group, a pentane-1,4-diyl group and a2-methylbutane-1,4-diyl group.

A^(a32) is preferably a methylene group or an ethylene group.

A^(a30) is preferably a single bond, *—CO—O— or *—CO—O-A^(a32)—CO—O—,more preferably a single bond, *—CO—O— or *—CO—O—CH₂—CO—O—, and stillmore preferably a single bond or *—CO—O—.

la is preferably 0, 1 or 2, more preferably 0 or 1, and still morepreferably 0.

Examples of the hydrocarbon group in R^(a34), R^(a35) and R^(a36)include an alkyl group, an alicyclic hydrocarbon group, an aromatichydrocarbon group, and groups formed by combining these groups.

Examples of the alkyl group include a methyl group, an ethyl group, apropyl group, a butyl group, a pentyl group, a hexyl group, a heptylgroup, an octyl group and the like.

The alicyclic hydrocarbon group may be either monocyclic or polycyclic.Examples of the monocyclic alicyclic hydrocarbon group includecycloalkyl groups such as a cyclopentyl group, a cyclohexyl group, acycloheptyl group and a cyclooctyl group. Examples of the polycyclicalicyclic hydrocarbon group include a decahydronaphthyl group, anadamantyl group, a norbornyl group and the following groups (*represents a bonding site).

Examples of the aromatic hydrocarbon group include aryl groups such as aphenyl group, a naphthyl group, an anthryl group, a biphenyl group and aphenanthryl group.

Examples of the combined group include groups obtained by combining theabove-mentioned alkyl group and alicyclic hydrocarbon group (e.g.,alkylcycloalkyl groups or cycloalkylalkyl groups, such as amethylcyclohexyl group, a dimethylcyclohexyl group, a methylnorbornylgroup, a cyclohexylmethyl group, an adamantylmethyl group, anadamantyldimethyl group and a norbornylethyl group), aralkyl groups suchas a benzyl group, aromatic hydrocarbon groups having an alkyl group (ap-methylphenyl group, a p-tert-butylphenyl group, a tolyl group, a xylylgroup, a cumenyl group, a mesityl group, a 2,6-diethylphenyl group, a2-methyl-6-ethylphenyl group, etc.), aromatic hydrocarbon groups havingan alicyclic hydrocarbon group (a p-cyclohexylphenyl group, ap-adamantylphenyl group, etc.), aryl-cycloalkyl groups such as aphenylcyclohexyl group and the like. Particularly, examples of R^(a36)include an alkyl group having 1 to 18 carbon atoms, an alicyclichydrocarbon group having 3 to 18 carbon atoms, an aromatic hydrocarbongroup having 6 to 18 carbon atoms, or a group formed by combining thesegroups.

R^(a34) is preferably a hydrogen atom.

R^(a35) is preferably a hydrogen atom, an alkyl group having 1 to 12carbon atoms or an alicyclic hydrocarbon group having 3 to 12 carbonatoms, and more preferably a methyl group or an ethyl group.

The hydrocarbon group of R^(a36) is preferably an alkyl group having 1to 18 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbonatoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or agroup formed by combining these groups, and more preferably an alkylgroup having 1 to 18 carbon atoms, an alicyclic hydrocarbon group having3 to 18 carbon atoms or an aralkyl group having 7 to 18 carbon atoms.The alkyl group and the alicyclic hydrocarbon group in R^(a36) arepreferably unsubstituted. The aromatic hydrocarbon group in R^(a36) ispreferably an aromatic ring having an aryloxy group having 6 to 10carbon atoms.

—OC(R^(a34)) (R^(a35))—O—R^(a36) in the structural unit (a1-4) iseliminated by contacting with an acid (e.g., p-toluenesulfonic acid) toform a hydroxy group.

—OC(R^(a34)) (R^(a35))—O—R^(a36) is preferably bonded to the o-positionor the p-position of the benzene ring, and more preferably thep-position.

The structural unit (a1-4) includes, for example, structural unitsderived from the monomers mentioned in JP 2010-204646 A. The structuralunit preferably includes structural units represented by formula(a1-4-1) to formula (a1-4-24) and a structural unit in which a hydrogenatom corresponding to R^(a32) in the structural unit (a1-4) issubstituted with a halogen atom, a haloalkyl group or an alkyl group,and more preferably structural units represented by formula (a1-4-1) toformula (a1-4-5), formula (a1-4-10), formula (a1-4-13), formula(a1-4-14), formula (a1-4-19) and formula (a1-4-20).

When the resin (A) includes the structural unit (a1-4), the content ispreferably 10 to 95 mol %, more preferably 15 to 90 mol %, still morepreferably 20 to 85 mol %, yet more preferably 20 to 70 mol %, andparticularly preferably 20 to 60 mol %, based on the total of allstructural units of the resin (A).

The structural unit derived from a (meth)acrylic monomer having a group(2) also includes a structural unit represented by formula (a1-5)(hereinafter sometimes referred to as “structural unit (a1-5)”).

In formula (a1-5),

-   -   R^(a8) represents an alkyl group having 1 to 6 carbon atoms        which may have a halogen atom, a hydrogen atom or a halogen        atom,    -   Z^(a1) represents a single bond or *—(CH₂)_(h3)—CO-L⁵⁴-, h3        represents an integer of 1 to 4, and * represents a bonding site        to L⁵¹,    -   L⁵¹, L⁵², L⁵³ and L⁵⁴ each independently represent —O— or —S—,    -   s1 represents an integer of 1 to 3, and    -   s1′ represents an integer of 0 to 3.

The halogen atom includes a fluorine atom and a chlorine atom and ispreferably a fluorine atom.

Examples of the alkyl group having 1 to 6 carbon atoms which may have ahalogen atom include a methyl group, an ethyl group, a propyl group, abutyl group, a pentyl group, a hexyl group, a heptyl group, an octylgroup, a fluoromethyl group and a trifluoromethyl group.

In formula (a1-5), R^(a8) is preferably a hydrogen atom, a methyl groupor a trifluoromethyl group,

-   -   L⁵¹ is preferably an oxygen atom,    -   one of L⁵² and L⁵³ is preferably —O— and the other one is        preferably —S—,    -   s1 is preferably 1,    -   s1′ is preferably an integer of 0 to 2, and    -   Z^(a1) is preferably a single bond or *—CH₂—CO—O—.

The structural unit (a1-5) includes, for example, structural unitsderived from the monomers mentioned in JP 2010-61117 A. Of thesestructural units, structural units represented by formula (a1-5-1) toformula (a1-5-4) are preferable, and structural units represented byformula (a1-5-1) or formula (a1-5-2) are more preferable.

When the resin (A) includes the structural unit (a1-5), the content ispreferably 1 to 50 mol %, more preferably 3 to 45 mol %, still morepreferably 5 to 40 mol %, and yet more preferably 5 to 30 mol %, basedon all structural units of the resin (A).

The structural unit (a1) also includes the following structural units.

When the resin (A) includes the above-mentioned structural units such as(a1-3-1) to (a1-3-7), the content is preferably 10 to 95 mol %, morepreferably 15 to 90 mol %, still more preferably 20 to 85 mol %, yetmore preferably 20 to 70 mol %, and particularly preferably 20 to 60 mol%, based on all structural units of the resin (A).

<Structural Unit (s)>

The structural unit (s) is derived from a monomer having no acid-labilegroup (hereinafter sometimes referred to as “monomer (s)”). It ispossible to use, as the monomer from which the structural unit (s) isderived, a monomer having no acid-labile group known in the resistfield.

The structural unit (s) preferably has a hydroxy group or a lactonering. When a resin including a structural unit having a hydroxy groupand having no acid-labile group (hereinafter sometimes referred to as“structural unit (a2)”) and/or a structural unit having a lactone ringand having no acid-labile group (hereinafter sometimes referred to as“structural unit (a3)”) is used in the resist composition of the presentinvention, it is possible to improve the resolution of a resist patternand the adhesion to a substrate.

<Structural Unit (a2)>

The hydroxy group possessed by the structural unit (a2) may be either analcoholic hydroxy group or a phenolic hydroxy group.

When a resist pattern is produced from the resist composition of thepresent invention, in the case of using, as an exposure source, highenergy rays such as KrF excimer laser (248 nm), electron beam or extremeultraviolet light (EUV), a structural unit (a2) having a phenolichydroxy group is preferably used, and the below-mentioned structuralunit (a2-A) is more preferably used, as the structural unit (a2). Whenusing ArF excimer laser (193 nm) or the like, a structural unit (a2)having an alcoholic hydroxy group is preferably used, and thebelow-mentioned structural unit (a2-1) is more preferably used, as thestructural unit (a2). The structural unit (a2) may be included alone, ortwo or more structural units may be included.

In the structural unit (a2), examples of the structural unit having aphenolic hydroxy group include a structural unit represented by formula(a2-A) (hereinafter sometimes referred to as “structural unit (a2-A)”):

wherein, in formula (a2-A),

-   -   R^(a50) represents a hydrogen atom, a halogen atom, or an alkyl        group having 1 to 6 carbon atoms which may have a halogen atom,    -   R^(a51) represents a halogen atom, a hydroxy group, an alkyl        group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6        carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms,        an alkoxyalkoxy group having 2 to 12 carbon atoms, an        alkylcarbonyl group having 2 to 4 carbon atoms, an        alkylcarbonyloxy group having 2 to 4 carbon atoms, an        acryloyloxy group or a methacryloyloxy group,    -   A^(a50) represents a single bond or        *—X^(a51)-(A^(a52)-X^(a52))_(nb)—, and * represents a bonding        site to carbon atoms to which —R^(a50) is bonded,    -   A^(a52) represents an alkanediyl group having 1 to 6 carbon        atoms,    -   X^(a51) and X^(a52) each independently represent —O—, —CO—O— or        —O—CO—,    -   nb represents 0 or 1, and    -   mb represents an integer of 0 to 4, and when mb is an integer of        2 or more, a plurality of R^(a51) may be the same or different        from each other.

Examples of the halogen atom in R^(a50) and R^(a51) include a fluorineatom, a chlorine atom and a bromine atom.

Examples of the alkyl group having 1 to 6 carbon atoms which may have ahalogen atom in R^(a50) include a trifluoromethyl group, adifluoromethyl group, a methyl group, a perfluoroethyl group, a2,2,2-trifluoroethyl group, a 1,1,2,2-tetrafluoroethyl group, an ethylgroup, a perfluoropropyl group, a 2,2,3,3,3-pentafluoropropyl group, apropyl group, a perfluorobutyl group, a 1,1,2,2,3,3,4,4-octafluorobutylgroup, a butyl group, a perfluoropentyl group, a2,2,3,3,4,4,5,5,5-nonafluoropentyl group, a pentyl group, a hexyl groupand a perfluorohexyl group.

R^(a50) is preferably a hydrogen atom or an alkyl group having 1 to 4carbon atoms, more preferably a hydrogen atom, a methyl group or anethyl group, and still more preferably a hydrogen atom or a methylgroup.

Examples of the alkyl group in R^(a51) include a methyl group, an ethylgroup, a propyl group, an isopropyl group, a butyl group, a sec-butylgroup, a tert-butyl group, a pentyl group and a hexyl group. The alkylgroup is preferably an alkyl group having 1 to 4 carbon atoms, morepreferably a methyl group or an ethyl group, and still more preferably amethyl group.

Examples of the alkoxy group in R^(a51) include a methoxy group, anethoxy group, a propoxy group, an isopropoxy group, a butoxy group, asec-butoxy group and a tert-butoxy group. The alkoxy group is preferablyan alkoxy group having 1 to 4 carbon atoms, more preferably a methoxygroup or an ethoxy group, and still more preferably a methoxy group.

Examples of the alkoxyalkyl group in R^(a51) include a methoxymethylgroup, an ethoxyethyl group, a propoxymethyl group, an isopropoxymethylgroup, a butoxymethyl group, a sec-butoxymethyl group and atert-butoxymethyl group. The alkoxyalkyl group is preferably analkoxyalkyl group having 2 to 8 carbon atoms, more preferably amethoxymethyl group or an ethoxyethyl group, and still more preferably amethoxymethyl group.

Examples of the alkoxyalkoxy group in R^(a51) include a methoxymethoxygroup, a methoxyethoxy group, an ethoxymethoxy group, an ethoxyethoxygroup, a propoxymethoxy group, an isopropoxymethoxy group, abutoxymethoxy group, a sec-butoxymethoxy group and a tert-butoxymethoxygroup. The alkoxyalkoxy group is preferably an alkoxyalkoxy group having2 to 8 carbon atoms, and more preferably a methoxyethoxy group or anethoxyethoxy group.

Examples of the alkylcarbonyl group in R^(a51) include an acetyl group,a propionyl group and a butyryl group. The alkylcarbonyl group ispreferably an alkylcarbonyl group having 2 to 3 carbon atoms, and morepreferably an acetyl group.

Examples of the alkylcarbonyloxy group in R^(a51) include an acetyloxygroup, a propionyloxy group and a butyryloxy group. The alkylcarbonyloxygroup is preferably an alkylcarbonyloxy group having 2 to 3 carbonatoms, and more preferably an acetyloxy group.

R^(a51) is preferably a halogen atom, a hydroxy group, an alkyl grouphaving 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atomsor an alkoxyalkoxy group having 2 to 8 carbon atoms, more preferably afluorine atom, an iodine atom, a hydroxy group, a methyl group, amethoxy group, an ethoxy group, an ethoxyethoxy group or anethoxymethoxy group, and still more preferably a fluorine atom, aniodine atom, a hydroxy group, a methyl group, a methoxy group or anethoxyethoxy group.

Examples of *—X^(a51)-(A^(a52)-X^(a52))_(nb)— include *—O—, *—CO—,*—O—CO—, *—CO—O-A^(a52)-CO—O—, *—O—CO-A^(a52)-O—, *—O-A^(a52)-CO—O—,*—CO—O-A^(a52)-O—CO— and *—O—CO-A^(a52)-O—CO—. Of these, *—CO—O—,*—CO—O-A^(a52)-CO—O— or *—O-A^(a52)-CO—O— is preferable.

Examples of the alkanediyl group in A^(a52) include a methylene group,an ethylene group, a propane-1,3-diyl group, a propane-1,2-diyl group, abutane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diylgroup, a butane-1,3-diyl group, a 2-methylpropane-1,3-diyl group, a2-methylpropane-1,2-diyl group, a pentane-1,4-diyl group and a2-methylbutane-1,4-diyl group.

A^(a52) is preferably a methylene group or an ethylene group.

A^(a50) is preferably a single bond, *—CO—O— or *—CO—O-A^(a52)-CO—O—,more preferably a single bond, *—CO—O— or *—CO—O—CH₂—CO—O—, and stillmore preferably a single bond or *—CO—O—.

mb is preferably 0, 1 or 2, more preferably 0 or 1, and still morepreferably 0.

At least one hydroxy group is preferably bonded to the meta-position orthe para-position of the benzene ring, and more preferably themeta-position. When the phenyl group has two or more hydroxy groups, twohydroxy groups are preferably bonded at the meta-position and thepara-position, respectively.

Examples of the structural unit (a2-A) include structural units derivedfrom the monomers mentioned in JP 2010-204634 A and JP 2012-12577 A.

Examples of the structural unit (a2-A) include structural unitsrepresented by formula (a2-2-1) to formula (a2-2-24), and a structuralunit in which a methyl group corresponding to R^(a50) in the structuralunit (a2-A) is substituted with a hydrogen atom, a halogen atom, ahaloalkyl group or other alkyl groups in structural units represented byformula (a2-2-1) to formula (a2-2-24). The structural unit (a2-A) ispreferably structural units represented by formula (a2-2-1) to formula(a2-2-4), a structural unit represented by formula (a2-2-6), astructural unit represented by formula (a2-2-8), structural unitsrepresented by formula (a2-2-12) to formula (a2-2-18), and a structuralunit in which a methyl group corresponding to R^(a50) in the structuralunit (a2-A) is substituted with a hydrogen atom in structural unitsrepresented by formula (a2-2-1) to formula (a2-2-4), a structural unitrepresented by formula (a2-2-6), a structural unit represented byformula (a2-2-8) and structural units represented by formula (a2-2-12)to formula (a2-2-18), more preferably a structural unit represented byformula (a2-2-3), a structural unit represented by formula (a2-2-4), astructural unit represented by formula (a2-2-8), structural unitsrepresented by formula (a2-2-12) to formula (a2-2-14), a structural unitrepresented by formula (a2-2-18), and a structural unit in which amethyl group corresponding to R^(a50) in the structural unit (a2-A) issubstituted with a hydrogen atom in a structural unit represented byformula (a2-2-3), a structural unit represented by formula (a2-2-4), astructural unit represented by formula (a2-2-8), structural unitsrepresented by formula (a2-2-12) to formula (a2-2-14) and a structuralunit represented by formula (a2-2-18), and still more preferably astructural unit represented by formula (a2-2-3), a structural unitrepresented by formula (a2-2-4), a structural unit represented byformula (a2-2-8), and a structural unit in which a methyl groupcorresponding to R^(a50) in the structural unit (a2-A) is substitutedwith a hydrogen atom in a structural unit represented by formula(a2-2-3), a structural unit represented by formula (a2-2-4) and astructural unit represented by formula (a2-2-8).

When the structural unit (a2-A) is included in the resin (A), thecontent of the structural unit (a2-A) is preferably 5 to 80 mol %, morepreferably 10 to 70 mol %, still more preferably 15 to 65 mol %, and yetmore preferably 20 to 65 mol %, based on all structural units.

The structural unit (a2-A) can be included in a resin (A) bypolymerizing, for example, with a structural unit (a1-4) and treatingwith an acid such as p-toluenesulfonic acid. The structural unit (a2-A)can also be included in the resin (A) by polymerizing withacetoxystyrene and treating with an alkali such as tetramethylammoniumhydroxide.

Examples of the structural unit having an alcoholic hydroxy group in thestructural unit (a2) include a structural unit represented by formula(a2-1) (hereinafter sometimes referred to as “structural unit (a2-1)”).

In formula (a2-1),

-   -   L^(a3) represents —O— or *—O—(CH₂)_(k2)—CO—O—,    -   k2 represents an integer of 1 to 7, and * represents a bonding        site to —CO—,    -   R^(a14) represents a hydrogen atom or a methyl group,    -   R^(a15) and R^(a16) each independently represent a hydrogen        atom, a methyl group or a hydroxy group, and    -   o1 represents an integer of 0 to 10.

In formula (a2-1), L^(a3) is preferably —O— or —O—(CH₂)_(f1)—CO—O— (f1represents an integer of 1 to 4), and more preferably —O—,

-   -   R^(a14) is preferably a methyl group,    -   R^(a15) is preferably a hydrogen atom,    -   R^(a16) is preferably a hydrogen atom or a hydroxy group, and    -   o1 is preferably an integer of 0 to 3, and more preferably 0 or        1.

The structural unit (a2-1) includes, for example, structural unitsderived from the monomers mentioned in JP 2010-204646 A. A structuralunit represented by any one of formula (a2-1-1) to formula (a2-1-6) ispreferable, a structural unit represented by any one of formula (a2-1-1)to formula (a2-1-4) is more preferable, and a structural unitrepresented by formula (a2-1-1) or formula (a2-1-3) is still morepreferable.

When the resin (A) includes the structural unit (a2-1), the content isusually 1 to 45 mol %, preferably 1 to 40 mol %, more preferably 1 to 35mol %, still more preferably 1 to 20 mol %, and yet more preferably 1 to10 mol %, based on all structural units of the resin (A).

<Structural Unit (a3)>

The lactone ring possessed by the structural unit (a3) may be amonocyclic ring such as a β-propiolactone ring, a γ-butyrolactone ringor a δ-valerolactone ring, or a condensed ring of a monocyclic lactonering and the other ring. Preferably, a γ-butyrolactone ring, anadamantanelactone ring or a bridged ring including a γ-butyrolactonering structure (e.g. a structural unit represented by the followingformula (a3-2)) is exemplified.

The structural unit (a3) is preferably a structural unit represented byformula (a3-1), formula (a3-2), formula (a3-3) or formula (a3-4). Thesestructural units may be included alone, or two or more structural unitsmay be included:

wherein, in formula (a3-1), formula (a3-2), formula (a3-3) and formula(a3-4),

-   -   L^(a4), Las and L^(a6) each independently represent —O— or a        group represented by *—O—(CH₂)_(k3)—CO—O— (k3 represents an        integer of 1 to 7),    -   L^(a7) represents —O—, *—O-L^(a8)-O—, *—O-L^(a8)-CO—O—,        *—O-L^(a8)-CO—O-L^(a9)-CO—O— or *—O-L^(a8)-O—CO-L^(a9)-O—,    -   L^(a8) and L^(a9) each independently represent an alkanediyl        group having 1 to 6 carbon atoms,    -   represents a bonding site to a carbonyl group,    -   R^(a18), R^(a19) and R^(a20) each independently represent a        hydrogen atom or a methyl group,    -   R^(a24) represents a hydrogen atom, a halogen atom, or an alkyl        group having 1 to 6 carbon atoms which may have a halogen atom,    -   X^(a3) represents —CH₂— or an oxygen atom,    -   R^(a21) represents an aliphatic hydrocarbon group having 1 to 4        carbon atoms,    -   R^(a22), R^(a23) and R^(a25) each independently represent a        carboxy group, a cyano group or an aliphatic hydrocarbon group        having 1 to 4 carbon atoms,    -   p1 represents an integer of 0 to 5,    -   q1 represents an integer of 0 to 3,    -   r1 represents an integer of 0 to 3,    -   w1 represents an integer of 0 to 8, and    -   when p1, q1, r1 and/or w1 is/are 2 or more, a plurality of        R^(a21), R^(a22), R^(a23) and/or R^(a25) may be the same or        different from each other.

Examples of the aliphatic hydrocarbon group in R^(a21), R^(a22), R^(a23)and R^(a25) include alkyl groups such as a methyl group, an ethyl group,a propyl group, an isopropyl group, a butyl group, a sec-butyl group anda tert-butyl group.

Examples of the halogen atom in R^(a24) include a fluorine atom, achlorine atom, a bromine atom and an iodine atom.

Examples of the alkyl group in R^(a24) include a methyl group, an ethylgroup, a propyl group, an isopropyl group, a butyl group, a sec-butylgroup, a tert-butyl group, a pentyl group and a hexyl group, and thealkyl group is preferably an alkyl group having 1 to 4 carbon atoms, andmore preferably a methyl group or an ethyl group.

Examples of the alkyl group having a halogen atom in R^(a24) include atrifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group,a perfluoroisopropyl group, a perfluorobutyl group, a perfluorosec-butylgroup, a perfluorotert-butyl group, a perfluoropentyl group, aperfluorohexyl group, a trichloromethyl group, a tribromomethyl group, atriiodomethyl group and the like.

Examples of the alkanediyl group in L^(a8) and L^(a9) include amethylene group, an ethylene group, a propane-1,3-diyl group, apropane-1,2-diyl group, a butane-1,4-diyl group, a pentane-1,5-diylgroup, a hexane-1,6-diyl group, a butane-1,3-diyl group, a2-methylpropane-1,3-diyl group, a 2-methylpropane-1,2-diyl group, apentane-1,4-diyl group and a 2-methylbutane-1,4-diyl group.

In formula (a3-1) to formula (a3-3), preferably, L^(a4) to L^(a6) areeach independently —O— or a group in which k3 is an integer of 1 to 4 in*—O—(CH₂)_(k3)—CO—O—, more preferably —O— and *—O—CH₂—CO—O—, and stillmore preferably an oxygen atom,

-   -   R^(a18) to R^(a21) are preferably a methyl group,    -   preferably, R^(a22) and R^(a23) are each independently a carboxy        group, a cyano group or a methyl group, and preferably, p1, q1        and r1 are each independently an integer of 0 to 2, and more        preferably 0 or 1.

In formula (a3-4), R^(a24) is preferably a hydrogen atom or an alkylgroup having 1 to 4 carbon atoms, more preferably a hydrogen atom, amethyl group or an ethyl group, and still more preferably a hydrogenatom or a methyl group,

-   -   R^(a25) is preferably a carboxy group, a cyano group or a methyl        group,    -   L^(a7) is preferably —O— or *—O-L^(a8)-CO—O—, and more        preferably —O—, —O—CH₂—CO—O— or —O—C₂H₄—CO—O—, and    -   w1 is preferably an integer of 0 to 2, and more preferably 0 or        1.

Particularly, formula (a3-4) is preferably formula (a3-4)′:

wherein R^(a24) and L^(a7) are the same as defined above.

Examples of the structural unit (a3) include structural units derivedfrom the monomers mentioned in JP 2010-204646 A, the monomers mentionedin JP 2000-122294 A and the monomers mentioned in JP 2012-41274 A. Thestructural unit (a3) is preferably a structural unit represented by anyone of formula (a3-1-1), formula (a3-1-2), formula (a3-2-1), formula(a3-2-2), formula (a3-3-1), formula (a3-3-2) and formula (a3-4-1) toformula (a3-4-12), and structural units in which methyl groupscorresponding to R^(a18), R^(a19), R^(a20) and R^(a24) in formula (a3-1)to formula (a3-4) are substituted with hydrogen atoms in the abovestructural units.

When the resin (A) includes the structural unit (a3), the total contentis usually 5 to 70 mol %, preferably 10 to 65 mol %, and more preferably10 to 60 mol %, based on all structural units of the resin (A).

Each content of the structural unit (a3-1), the structural unit (a3-2),the structural unit (a3-3) or the structural unit (a3-4) is preferably 5to 60 mol %, more preferably 5 to 50 mol %, and still more preferably 10to 50 mol %, based on all structural units of the resin (A).

<Structural Unit (a4)>

Examples of the structural unit (a4) include the following structuralunit:

wherein, in formula (a4),

-   -   R⁴¹ represents a hydrogen atom or a methyl group, and    -   R⁴² represents a saturated hydrocarbon group having 1 to 24        carbon atoms which has a fluorine atom, and —CH₂— included in        the saturated hydrocarbon group may be replaced by —O— or —CO—.

Examples of the saturated hydrocarbon group represented by R⁴² include achain hydrocarbon group and a monocyclic or polycyclic alicyclichydrocarbon group, and groups formed by combining these groups.

Examples of the chain hydrocarbon group include a methyl group, an ethylgroup, a propyl group, a butyl group, a pentyl group, a hexyl group, aheptyl group, an octyl group, a decyl group, a dodecyl group, apentadecyl group, a hexadecyl group, a heptadecyl group and an octadecylgroup. Examples of the monocyclic or polycyclic alicyclic hydrocarbongroup include cycloalkyl groups such as a cyclopentyl group, acyclohexyl group, a cycloheptyl group and a cyclooctyl group; andpolycyclic alicyclic hydrocarbon groups such as a decahydronaphthylgroup, an adamantyl group, a norbornyl group and the following groups (*represents a bonding site).

Examples of the group formed by combination include groups formed bycombining one or more alkyl groups or one or more alkanediyl groups withone or more alicyclic hydrocarbon groups, for example, an -alkanediylgroup-alicyclic hydrocarbon group, an -alicyclic hydrocarbon group-alkylgroup, an -alkanediyl group-alicyclic hydrocarbon group-alkyl group andthe like.

Examples of the structural unit (a4) include a structural unitrepresented by at least one selected from the group consisting offormula (a4-0), formula (a4-1), formula (a4-2), formula (a4-3) andformula (a4-4):

wherein, in formula (a4-0),

-   -   R⁵ represents a hydrogen atom or a methyl group,    -   L^(4a) represents a single bond or a divalent aliphatic        saturated hydrocarbon group having 1 to 4 carbon atoms,    -   L^(3a) represents a perfluoroalkanediyl group having 1 to 8        carbon atoms or a perfluorocycloalkanediyl group having 3 to 12        carbon atoms, and    -   R⁶ represents a hydrogen atom or a fluorine atom.

Examples of the divalent aliphatic saturated hydrocarbon group in L^(4a)include linear alkanediyl groups such as a methylene group, an ethylenegroup, a propane-1,3-diyl group and a butane-1,4-diyl group; andbranched alkanediyl groups such as an ethane-1,1-diyl group, apropane-1,2-diyl group, a butane-1,3-diyl group, a2-methylpropane-1,3-diyl group and a 2-methylpropane-1,2-diyl group.

Examples of the perfluoroalkanediyl group in L³a include adifluoromethylene group, a perfluoroethylene group, aperfluoropropane-1,1-diyl group, a perfluoropropane-1,3-diyl group, aperfluoropropane-1,2-diyl group, a perfluoropropane-2,2-diyl group, aperfluorobutane-1,4-diyl group, a perfluorobutane-2,2-diyl group, aperfluorobutane-1,2-diyl group, a perfluoropentane-1,5-diyl group, aperfluoropentane-2,2-diyl group, a perfluoropentane-3,3-diyl group, aperfluorohexane-1,6-diyl group, a perfluorohexane-2,2-diyl group, aperfluorohexane-3,3-diyl group, a perfluoroheptane-1,7-diyl group, aperfluoroheptane-2,2-diyl group, a perfluoroheptane-3,4-diyl group, aperfluoroheptane-4,4-diyl group, a perfluorooctane-1,8-diyl group, aperfluorooctane-2,2-diyl group, a perfluorooctane-3,3-diyl group, aperfluorooctane-4,4-diyl group and the like.

Examples of the perfluorocycloalkanediyl group in L³a include aperfluorocyclohexanediyl group, a perfluorocyclopentanediyl group, aperfluorocycloheptanediyl group, a perfluoroadamantanediyl group and thelike.

L^(4a) is preferably a single bond, a methylene group or an ethylenegroup, and more preferably a single bond or a methylene group.

L^(3a) is preferably a perfluoroalkanediyl group having 1 to 6 carbonatoms, and more preferably a perfluoroalkanediyl group having 1 to 3carbon atoms.

Examples of the structural unit (a4-0) include the following structuralunits, and structural units in which a methyl group corresponding to R⁵in the structural unit (a4-0) in the following structural units issubstituted with a hydrogen atom:

Examples of the structural unit (a4) include a structural unitrepresented by formula (a4-1):

wherein, in formula (a4-1),

-   -   R^(a41) represents a hydrogen atom or a methyl group,    -   R^(a42) represents a saturated hydrocarbon group having 1 to 20        carbon atoms which may have a substituent, and —CH₂-included in        the saturated hydrocarbon group may be replaced by —O— or —CO—,    -   A^(a41) represents an alkanediyl group having 1 to 6 carbon        atoms which may have a substituent or a group represented by        formula (a-g1), in which at least one of A^(a41) and R^(a42)        has, as a substituent, a halogen atom (preferably a fluorine        atom):

-   -   [in which, in formula (a-g1),    -   s represents 0 or 1,    -   A^(a42) and A^(a44) each independently represent a divalent        saturated hydrocarbon group having 1 to 5 carbon atoms which may        have a substituent,    -   A^(a43) represents a single bond or a divalent aliphatic        hydrocarbon group having 1 to 5 carbon atoms which may have a        substituent,    -   X^(a41) and X^(a42) each independently represent —O—, —CO—,        —CO—O— or —O—CO—, in which the total number of carbon atoms of        A^(a42), A^(a43), A^(a44), X^(a41) and X^(a42) is 7 or less],        and    -   * represents a bonding site and * at the right side represents a        bonding site to —O—CO—R^(a42).

Examples of the saturated hydrocarbon group in R^(a42) include a chainsaturated hydrocarbon group and a monocyclic or polycyclic saturatedalicyclic hydrocarbon group, and groups formed by combining thesegroups.

Examples of the chain saturated hydrocarbon group include a methylgroup, an ethyl group, a propyl group, a butyl group, a pentyl group, ahexyl group, a heptyl group, an octyl group, a decyl group, a dodecylgroup, a pentadecyl group, a hexadecyl group, a heptadecyl group and anoctadecyl group.

Examples of the monocyclic or polycyclic alicyclic saturated hydrocarbongroup include cycloalkyl groups such as a cyclopentyl group, acyclohexyl group, a cycloheptyl group and a cyclooctyl group; andpolycyclic alicyclic saturated hydrocarbon groups such as adecahydronaphthyl group, an adamantyl group, a norbornyl group and thefollowing groups (* represents a bonding site).

Examples of the group formed by combination include groups formed bycombining one or more alkyl groups or one or more alkanediyl groups withone or more alicyclic saturated hydrocarbon groups, for example, an-alkanediyl group-alicyclic saturated hydrocarbon group, an -alicyclicsaturated hydrocarbon group-alkyl group, an -alkanediyl group-alicyclicsaturated hydrocarbon group-alkyl group and the like.

Examples of the substituent which may be possessed by R^(a42) include atleast one selected from the group consisting of a halogen atom and agroup represented by formula (a-g3). Examples of the halogen atominclude a fluorine atom, a chlorine atom, a bromine atom and an iodineatom, and a fluorine atom is preferable:*—X^(a43)-A^(a45)  (a-g3)wherein, in formula (a-g3),

-   -   X^(a43) represents an oxygen atom, a carbonyl group, *—O—CO— or        *—CO—O—,    -   A^(a45) represents an aliphatic hydrocarbon group having 1 to 17        carbon atoms which may have a halogen atom, and * represents a        bonding site to R^(a42).

In R^(a42)—X^(a43)-A^(a45), when R^(a42) has no halogen atom, A^(a45)represents an aliphatic hydrocarbon group having 1 to 17 carbon atomshaving at least one halogen atom.

Examples of the aliphatic hydrocarbon group in A^(a45) include alkylgroups such as a methyl group, an ethyl group, a propyl group, a butylgroup, a pentyl group, a hexyl group, a heptyl group, an octyl group, adecyl group, a dodecyl group, a pentadecyl group, a hexadecyl group, aheptadecyl group and an octadecyl group;

monocyclic alicyclic hydrocarbon groups such as a cyclopentyl group, acyclohexyl group, a cycloheptyl group and a cyclooctyl group; andpolycyclic alicyclic hydrocarbon groups such as a decahydronaphthylgroup, an adamantyl group, a norbornyl group and the following groups (*represents a bonding site).

Examples of the group formed by combination include groups obtained bycombining one or more alkyl groups or one or more alkanediyl groups withone or more alicyclic hydrocarbon groups, for example, an -alkanediylgroup-alicyclic hydrocarbon group, an -alicyclic hydrocarbon group-alkylgroup, an -alkanediyl group-alicyclic hydrocarbon group-alkyl group andthe like.

R^(a42) is preferably an aliphatic hydrocarbon group which may have ahalogen atom, and more preferably an alkyl group having a halogen atomand/or an aliphatic hydrocarbon group having a group represented byformula (a-g3).

When R^(a42) is an aliphatic hydrocarbon group having a halogen atom, analiphatic hydrocarbon group having a fluorine atom is preferable, aperfluoroalkyl group or a perfluorocycloalkyl group is more preferable,a perfluoroalkyl group having 1 to 6 carbon atoms is still morepreferable, and a perfluoroalkyl group having 1 to 3 carbon atoms isparticularly preferable. Examples of the perfluoroalkyl group include aperfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group,a perfluorobutyl group, a perfluoropentyl group, a perfluorohexyl group,a perfluoroheptyl group and a perfluorooctyl group. Examples of theperfluorocycloalkyl group include a perfluorocyclohexyl group and thelike.

When R^(a42) is an aliphatic hydrocarbon group having a grouprepresented by formula (a-g3), the total number of carbon atoms ofR^(a42) is preferably 15 or less, and more preferably 12 or less,including the number of carbon atoms included in the group representedby formula (a-g3). When having the group represented by formula (a-g3)as the substituent, the number thereof is preferably 1.

When R^(a42) is an aliphatic hydrocarbon group having the grouprepresented by formula (a-g3), R^(a42) is still more preferably a grouprepresented by formula (a-g2):*-A^(a46)-X^(a44)-A^(a47)  (a-g2)wherein, in formula (a-g2),

-   -   A^(a46) represents a divalent aliphatic hydrocarbon group having        1 to 17 carbon atoms which may have a halogen atom,    -   X^(a44) represents **—O—CO— or **—CO—O— (** represents a bonding        site to A^(a46)),    -   A^(a47) represents an aliphatic hydrocarbon group having 1 to 17        carbon atoms which may have a halogen atom,    -   the total number of carbon atoms of A^(a46), A^(a47) and X^(a44)        is 18 or less, and at least one of A^(a46) and A^(a47) has at        least one halogen atom, and    -   represents a bonding site to a carbonyl group.

The number of carbon atoms of the aliphatic hydrocarbon group as forA^(a46) is preferably 1 to 6, and more preferably 1 to 3.

The number of carbon atoms of the aliphatic hydrocarbon group as forA^(a47) is preferably 4 to 15, and more preferably 5 to 12, and A^(a47)is still more preferably a cyclohexyl group or an adamantyl group.

Preferred structures of the group represented by formula (a-g2) are thefollowing structures (* represents a bonding site to a carbonyl group).

Examples of the alkanediyl group in A^(a41) include linear alkanediylgroups such as a methylene group, an ethylene group, a propane-1,3-diylgroup, a butane-1,4-diyl group, a pentane-1,5-diyl group and ahexane-1,6-diyl group; and branched alkanediyl groups such as apropane-1,2-diyl group, a butane-1,3-diyl group, a2-methylpropane-1,2-diyl group, a 1-methylbutane-1,4-diyl group and a2-methylbutane-1,4-diyl group.

Examples of the substituent in the alkanediyl group as for A^(a41)include a hydroxy group and an alkoxy group having 1 to 6 carbon atoms.

A^(a41) is preferably an alkanediyl group having 1 to 4 carbon atoms,more preferably an alkanediyl group having 2 to 4 carbon atoms, andstill more preferably an ethylene group.

Examples of the divalent saturated hydrocarbon group represented byA^(a42), A^(a43) and A^(a44) in the group represented by formula (a-g1)include a linear or branched alkanediyl group and a monocyclic orpolycyclic divalent alicyclic hydrocarbon group, and groups formed bycombining an alkanediyl group and a divalent alicyclic hydrocarbongroup. Specific examples thereof include a methylene group, an ethylenegroup, a propane-1,3-diyl group, a propane-1,2-diyl group, abutane-1,4-diyl group, a 1-methylpropane-1,3-diyl group, a2-methylpropane-1,3-diyl group, a 2-methylpropane-1,2-diyl group and thelike.

Examples of the substituent of the divalent saturated hydrocarbon grouprepresented by A^(a42), A^(a43) and A^(a44) include a hydroxy group andan alkoxy group having 1 to 6 carbon atoms.

s is preferably 0.

In the group represented by formula (a-g1), examples of the group inwhich X^(a42) is —O—, —CO—, —CO—O— or —O—CO-include the followinggroups. In the following exemplification, * and ** each represent abonding site, and ** represents a bonding site to —O—CO—R^(a42).

Examples of the structural unit represented by formula (a4-1) includethe following structural units, and structural units in which a methylgroup corresponding to R^(a41) in the structural unit represented byformula (a4-1) in the following structural units is substituted with ahydrogen atom.

Examples of the structural unit (a4) also include a structural unitrepresented by formula (a4-2):

wherein, in formula (a4-2),

-   -   R^(f5) represents a hydrogen atom or a methyl group,    -   L⁴⁴ represents an alkanediyl group having 1 to 6 carbon atoms,        and —CH₂— included in the alkanediyl group may be replaced by        —O— or —CO—,    -   R^(f6) represents a saturated hydrocarbon group having 1 to 20        carbon atoms having a fluorine atom, and the upper limit of the        total number of carbon atoms of L⁴⁴ and R^(f6) is 21.

Examples of the alkanediyl group having 1 to 6 carbon atoms of L⁴⁴include those which are the same as mentioned as for the alkanediylgroup in A^(a41).

Examples of the saturated hydrocarbon group of R^(f6) include the samegroups as mentioned as for R^(a42) The alkanediyl group having 1 to 6carbon atoms in L⁴⁴ is preferably an alkanediyl group having 2 to 4carbon atoms, and more preferably an ethylene group.

The structural unit represented by formula (a4-2) includes, for example,structural units represented by formula (a4-1-1) to formula (a4-1-11) Astructural unit in which a methyl group corresponding to R^(f5) in thestructural unit (a4-2) is substituted with a hydrogen atom is alsoexemplified as the structural unit represented by formula (a4-2).

Examples of the structural unit (a4) also include a structural unitrepresented by formula (a4-3):

wherein, in formula (a4-3),

-   -   R^(f7) represents a hydrogen atom or a methyl group,    -   L⁵ represents an alkanediyl group having 1 to 6 carbon atoms,    -   A^(f13) represents a divalent saturated hydrocarbon group having        1 to 18 carbon atoms which may have a fluorine atom,    -   X^(f12) represents *—O—CO— or *—CO—O— (* represents a bonding        site to A^(f13)),    -   A^(f14) represents a saturated hydrocarbon group having 1 to 17        carbon atoms which may have a fluorine atom, and    -   at least one of A^(f13) and A^(f14) has a fluorine atom, and the        upper limit of the total number of carbon atoms of L⁵, A^(f13)        and A^(f14) is 20.

Examples of the alkanediyl group in L⁵ include those which are the sameas mentioned as for the alkanediyl group in A^(a41).

The divalent saturated hydrocarbon group which may have a fluorine atomin A^(f13) is preferably a divalent chain saturated hydrocarbon groupwhich may have a fluorine atom and a divalent alicyclic saturatedhydrocarbon group which may have a fluorine atom, and more preferably aperfluoroalkanediyl group.

Examples of the divalent chain saturated hydrocarbon group which mayhave a fluorine atom include alkanediyl groups such as a methylenegroup, an ethylene group, a propanediyl group, a butanediyl group and apentanediyl group; and perfluoroalkanediyl groups such as adifluoromethylene group, a perfluoroethylene group, aperfluoropropanediyl group, a perfluorobutanediyl group and aperfluoropentanediyl group.

The divalent alicyclic saturated hydrocarbon group which may have afluorine atom may be either monocyclic or polycyclic. Examples of themonocyclic group include a cyclohexanediyl group and aperfluorocyclohexanediyl group. Examples of the polycyclic group includean adamantanediyl group, a norbornanediyl group, aperfluoroadamantanediyl group and the like.

Examples of the saturated hydrocarbon group and the saturatedhydrocarbon group which may have a fluorine atom as for A^(f14) includethe same groups as mentioned as for R^(a42). Of these groups, preferableare fluorinated alkyl groups such as a trifluoromethyl group, adifluoromethyl group, a methyl group, a perfluoroethyl group, a2,2,2-trifluoroethyl group, a 1,1,2,2-tetrafluoroethyl group, an ethylgroup, a perfluoropropyl group, a 2,2,3,3,3-pentafluoropropyl group, apropyl group, a perfluorobutyl group, a 1,1,2,2,3,3,4,4-octafluorobutylgroup, a butyl group, a perfluoropentyl group, a2,2,3,3,4,4,5,5,5-nonafluoropentyl group, a pentyl group, a hexyl group,a perfluorohexyl group, a heptyl group, a perfluoroheptyl group, anoctyl group and a perfluorooctyl group; a cyclopropylmethyl group, acyclopropyl group, a cyclobutylmethyl group, a cyclopentyl group, acyclohexyl group, a perfluorocyclohexyl group, an adamantyl group, anadamantylmethyl group, an adamantyldimethyl group, a norbornyl group, anorbornylmethyl group, a perfluoroadamantyl group, aperfluoroadamantylmethyl group and the like.

In formula (a4-3), L⁵ is preferably an ethylene group.

The divalent saturated hydrocarbon group as for A^(f13) is preferably agroup including a divalent chain saturated hydrocarbon group having 1 to6 carbon atoms and a divalent alicyclic saturated hydrocarbon grouphaving 3 to 12 carbon atoms, and more preferably a divalent chainsaturated hydrocarbon group having 2 to 3 carbon atoms.

The saturated hydrocarbon group as for A^(f14) is preferably a groupwhich has a chain saturated hydrocarbon group having 3 to 12 carbonatoms and an alicyclic saturated hydrocarbon group having 3 to 12 carbonatoms, and more preferably a group which has a chain saturatedhydrocarbon group having 3 to 10 carbon atoms and an alicyclic saturatedhydrocarbon group having 3 to 10 carbon atoms. Of these groups, A^(f14)is preferably a group which has an alicyclic saturated hydrocarbon grouphaving 3 to 12 carbon atoms, and more preferably a cyclopropylmethylgroup, a cyclopentyl group, a cyclohexyl group, a norbornyl group and anadamantyl group.

The structural unit represented by formula (a4-3) includes, for example,structural units represented by formula (a4-1′-1) to formula (a4-1′-11).A structural unit in which a methyl group corresponding to R^(f7) in thestructural unit (a4-3) is substituted with a hydrogen atom is alsoexemplified as the structural unit represented by formula (a4-3).

It is also possible to exemplify, as the structural unit (a4), astructural unit represented by formula (a4-4):

wherein, in formula (a4-4),

-   -   R^(f21) represents a hydrogen atom or a methyl group,    -   A^(f21) represents —(CH₂)_(j1)—, —(CH₂)_(j2)—O—(CH₂)_(j3)— or        —(CH₂)_(j4)—CO—O— (CH₂)_(j5)—,    -   j1 to j5 each independently represent an integer of 1 to 6, and    -   R^(f22) represents a saturated hydrocarbon group having 1 to 10        carbon atoms having a fluorine atom.

Examples of the saturated hydrocarbon group of R^(f22) include thosewhich are the same as the saturated hydrocarbon group represented byR^(a42). R^(f22) is preferably an alkyl group having 1 to 10 carbonatoms which has a fluorine atom or an alicyclic hydrocarbon group having1 to 10 carbon atoms which has a fluorine atom, more preferably an alkylgroup having 1 to 10 carbon atoms which has a fluorine atom, and stillmore preferably an alkyl group having 1 to 6 carbon atoms which has afluorine atom.

In formula (a4-4), A^(f21) is preferably —(CH₂)_(j1)—, more preferablyan ethylene group or a methylene group, and still more preferably amethylene group.

The structural unit represented by formula (a4-4) includes, for example,the following structural units and structural units in which a methylgroup corresponding to R^(f21) in the structural unit (a4-4) issubstituted with a hydrogen atom in structural units represented by thefollowing formulas.

When the resin (A) includes the structural unit (a4), the content ispreferably 1 to 20 mol %, more preferably 2 to 15 mol %, and still morepreferably 3 to 10 mol %, based on all structural units of the resin(A).

<Structural Unit (a5)>

Examples of a non-leaving hydrocarbon group possessed by the structuralunit (a5) include groups having a linear, branched or cyclic hydrocarbongroup. Of these, the structural unit (a5) is preferably a group havingan alicyclic hydrocarbon group.

The structural unit (a5) includes, for example, a structural unitrepresented by formula (a5-1):

wherein, in formula (a5-1),

-   -   R⁵¹ represents a hydrogen atom or a methyl group,    -   R⁵² represents an alicyclic hydrocarbon group having 3 to 18        carbon atoms, and a hydrogen atom included in the alicyclic        hydrocarbon group may be substituted with an aliphatic        hydrocarbon group having 1 to 8 carbon atoms, and    -   L⁵⁵ represents a single bond or a divalent saturated hydrocarbon        group having 1 to 18 carbon atoms, and —CH₂— included in the        saturated hydrocarbon group may be replaced by —O— or —CO—.

The alicyclic hydrocarbon group in R⁵² may be either monocyclic orpolycyclic. The monocyclic alicyclic hydrocarbon group includes, forexample, a cyclopropyl group, a cyclobutyl group, a cyclopentyl groupand a cyclohexyl group. The polycyclic alicyclic hydrocarbon groupincludes, for example, an adamantyl group and a norbornyl group.

The aliphatic hydrocarbon group having 1 to 8 carbon atoms includes, forexample, alkyl groups such as a methyl group, an ethyl group, a propylgroup, an isopropyl group, a butyl group, a sec-butyl group, atert-butyl group, a pentyl group, a hexyl group, an octyl group and a2-ethylhexyl group.

Examples of the alicyclic hydrocarbon group having a substituentincludes a 3-methyladamantyl group and the like.

R⁵² is preferably an unsubstituted alicyclic hydrocarbon group having 3to 18 carbon atoms, and more preferably an adamantyl group, a norbornylgroup or a cyclohexyl group.

Examples of the divalent saturated hydrocarbon group in L⁵⁵ include adivalent chain saturated hydrocarbon group and a divalent alicyclicsaturated hydrocarbon group, and a divalent chain saturated hydrocarbongroup is preferable.

The divalent chain saturated hydrocarbon group includes, for example,alkanediyl groups such as a methylene group, an ethylene group, apropanediyl group, a butanediyl group and a pentanediyl group.

The divalent alicyclic saturated hydrocarbon group may be eithermonocyclic or polycyclic. Examples of the monocyclic alicyclic saturatedhydrocarbon group include cycloalkanediyl groups such as acyclopentanediyl group and a cyclohexanediyl group. Examples of thepolycyclic divalent alicyclic saturated hydrocarbon group include anadamantanediyl group and a norbornanediyl group.

The group in which —CH₂— included in the divalent saturated hydrocarbongroup represented by L⁵⁵ is replaced by —O— or —CO— includes, forexample, groups represented by formula (L1-1) to formula (L1-4). In thefollowing formulas, * and ** each represent a bonding site, and *represents a bonding site to an oxygen atom.

In formula (L1-1),

-   -   X^(x1) represents *—O—CO— or *—CO—O— (* represents a bonding        site to L^(x1)),    -   L^(x1) represents a divalent aliphatic saturated hydrocarbon        group having 1 to 16 carbon atoms,    -   L^(x2) represents a single bond or a divalent aliphatic        saturated hydrocarbon group having 1 to 15 carbon atoms, and the        total number of carbon atoms of L^(x1) and L^(x2) is 16 or less.

In formula (L1-2),

-   -   L^(x3) represents a divalent aliphatic saturated hydrocarbon        group having 1 to 17 carbon atoms,    -   L^(x4) represents a single bond or a divalent aliphatic        saturated hydrocarbon group having 1 to 16 carbon atoms, and the        total number of carbon atoms of L^(x3) and L^(x4) is 17 or less.

In formula (L1-3),

-   -   L^(x5) represents a divalent aliphatic saturated hydrocarbon        group having 1 to 15 carbon atoms,    -   L^(x6) and L^(x7) each independently represent a single bond or        a divalent aliphatic saturated hydrocarbon group having 1 to 14        carbon atoms, and    -   the total number of carbon atoms of L^(x5), L^(x6) and L^(x7) is        15 or less.

In formula (L1-4),

-   -   L^(x8) and L^(x9) represent a single bond or a divalent        aliphatic saturated hydrocarbon group having 1 to 12 carbon        atoms,    -   W^(x1) represents a divalent alicyclic saturated hydrocarbon        group having 3 to 15 carbon atoms, and    -   the total number of carbon atoms of L^(x8), L^(x9) and W^(x1) is        15 or less.

L^(x1) is preferably a divalent aliphatic saturated hydrocarbon grouphaving 1 to 8 carbon atoms, and more preferably a methylene group or anethylene group.

L^(x2) is preferably a single bond or a divalent aliphatic saturatedhydrocarbon group having 1 to 8 carbon atoms, and more preferably asingle bond.

L^(x3) is preferably a divalent aliphatic saturated hydrocarbon grouphaving 1 to 8 carbon atoms.

L^(x4) is preferably a single bond or a divalent aliphatic saturatedhydrocarbon group having 1 to 8 carbon atoms.

L^(x5) is preferably a divalent aliphatic saturated hydrocarbon grouphaving 1 to 8 carbon atoms, and more preferably a methylene group or anethylene group.

L^(x6) is preferably a single bond or a divalent aliphatic saturatedhydrocarbon group having 1 to 8 carbon atoms, and more preferably amethylene group or an ethylene group.

L^(x7) is preferably a single bond or a divalent aliphatic saturatedhydrocarbon group having 1 to 8 carbon atoms.

L^(x8) is preferably a single bond or a divalent aliphatic saturatedhydrocarbon group having 1 to 8 carbon atoms, and more preferably asingle bond or a methylene group.

L^(x9) is preferably a single bond or a divalent aliphatic saturatedhydrocarbon group having 1 to 8 carbon atoms, and more preferably asingle bond or a methylene group.

W^(x1) is preferably a divalent alicyclic saturated hydrocarbon grouphaving 3 to 10 carbon atoms, and more preferably a cyclohexanediyl groupor an adamantanediyl group.

The group represented by formula (L1-1) includes, for example, thefollowing divalent groups.

The group represented by formula (L1-2) includes, for example, thefollowing divalent groups.

The group represented by formula (L1-3) includes, for example, thefollowing divalent groups.

The group represented by formula (L1-4) includes, for example, thefollowing divalent groups.

L⁵⁵ is preferably a single bond or a group represented by formula(L1-1).

Examples of the structural unit (a5-1) include the following structuralunits and structural units in which a methyl group corresponding to R⁵¹in the structural unit (a5-1) in the following structural units issubstituted with a hydrogen atom.

When the resin (A) includes the structural unit (a5), the content ispreferably 1 to 30 mol %, more preferably 2 to 20 mol %, and still morepreferably 3 to 15 mol %, based on all structural units of the resin(A).

<Structural Unit (a6)>

The structural unit (a6) is a structural unit having an —SO₂— group, andit is preferable to have an —SO₂— group in a side chain.

The structural unit having an —SO₂— group may have a linear structurehaving an —SO₂— group, a branched structure having an —SO₂— group, or acyclic structure (monocyclic and polycyclic structure) having an —SO₂—group. The structural unit is preferably a structural unit which has acyclic structure having an —SO₂— group, and more preferably a structuralunit which has a cyclic structure (sultone ring) having —SO₂—O—.

Examples of the sultone ring include rings represented by the followingformula (T¹-1), formula (T¹-2), formula (T¹-3) and formula (T¹-4). Thebonding site can be any position. The sultone ring may be monocyclic,and is preferably polycyclic. The polycyclic sultone ring means abridged ring which has —SO₂—O— as an atomic group constituting the ring,and examples thereof include rings represented by formula (T¹-1) andformula (T¹-2). The sultone ring may have, as the atomic groupconstituting the ring, a heteroatom, in addition to —SO₂—O—, like thering represented by formula (T¹-2). Examples of the heteroatom includean oxygen atom, a sulfur atom or a nitrogen atom, and an oxygen atom ispreferable.

The sultone ring may have a substituent, and examples of the substituentinclude an alkyl group having 1 to 12 carbon atoms which may have ahalogen atom or a hydroxy group, a halogen atom, a hydroxy group, acyano group, an alkoxy group having 1 to 12 carbon atoms, an aryl grouphaving 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbonatoms, a glycidyloxy group, an alkoxycarbonyl group having 2 to 12carbon atoms and an alkylcarbonyl group having 2 to 4 carbon atoms.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom.

Examples of the alkyl group include a methyl group, an ethyl group, apropyl group, a butyl group, a pentyl group, a hexyl group, an octylgroup and a decyl group, and the alkyl group is preferably an alkylgroup having 1 to 6 carbon atoms, and more preferably a methyl group.

Examples of the alkyl group having a halogen atom include atrifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group,a perfluoroisopropyl group, a perfluorobutyl group, a perfluorosec-butylgroup, a perfluorotert-butyl group, a perfluoropentyl group, aperfluorohexyl group, a trichloromethyl group, a tribromomethyl groupand a triiodomethyl group, and a trifluoromethyl group is preferable.

Examples of the alkyl group having a hydroxy group include hydroxyalkylgroups such as a hydroxymethyl group and a 2-hydroxyethyl group.

Examples of the alkoxy group include a methoxy group, an ethoxy group, apropoxy group, a butoxy group, a pentyloxy group, a hexyloxy group, aheptyloxy group, an octyloxy group, a decyloxy group and a dodecyloxygroup.

Examples of the aryl group include a phenyl group, a naphthyl group, ananthryl group, a p-methylphenyl group, a p-tert-butylphenyl group, ap-adamantylphenyl group, a tolyl group, a xylyl group, a cumyl group, amesityl group, a biphenyl group, a phenanthryl group, a2,6-diethylphenyl group and a 2-methyl-6-ethylphenyl group.

Examples of the aralkyl group include a benzyl group, a phenethyl group,a phenylpropyl group, a naphthylmethyl group and a naphthylethyl group.

Examples of the alkoxycarbonyl group include groups in which an alkoxygroup is bonded with a carbonyl group, such as a methoxycarbonyl groupor an ethoxycarbonyl group, and preferably include an alkoxycarbonylgroup having 6 or less carbon atoms and more preferably include amethoxycarbonyl group.

Examples of the alkylcarbonyl group include an acetyl group, a propionylgroup and a butyryl group.

From the viewpoint that it is easy to produce a monomer from which thestructural unit (a6) is derived, a sultone ring having no substituent ispreferable.

The sultone ring is preferably a ring represented by the followingformula (T1′):

wherein, in formula (T1′),

-   -   X¹¹ represents an oxygen atom, a sulfur atom or a methylene        group,    -   R⁴¹ represents an alkyl group having 1 to 12 carbon atoms which        may have a halogen atom or a hydroxy group, a halogen atom, a        hydroxy group, a cyano group, an alkoxy group having 1 to 12        carbon atoms, an aryl group having 6 to 12 carbon atoms, an        aralkyl group having 7 to 12 carbon atoms, a glycidyloxy group,        an alkoxycarbonyl group having 2 to 12 carbon atoms, or an        alkylcarbonyl group having 2 to 4 carbon atoms,    -   ma represents an integer of 0 to 9, and when ma is 2 or more, a        plurality of R⁴¹ may be the same or different, and    -   the bonding site may be at any position.

X¹¹ is preferably an oxygen atom or a methylene group, and morepreferably a methylene group.

Examples of R⁴¹ include those which are the same as the substituent ofthe sultone ring, and an alkyl group having 1 to 12 carbon atoms whichmay have a halogen atom or a hydroxy group is preferable.

The sultone ring is more preferably a ring represented by formula (T1):

wherein, in formula (T1),

-   -   R⁸ represents an alkyl group having 1 to 12 carbon atoms which        may have a halogen atom or a hydroxy group, a halogen atom, a        hydroxy group, a cyano group, an alkoxy group having 1 to 12        carbon atoms, an aryl group having 6 to 12 carbon atoms, an        aralkyl group having 7 to 12 carbon atoms, a glycidyloxy group,        an alkoxycarbonyl group having 2 to 12 carbon atoms, or an        alkylcarbonyl group having 2 to 4 carbon atoms,    -   m represents an integer of 0 to 9, and when m is 2 or more, a        plurality of R⁸ may be the same or different, and    -   the bonding site may be at any position.

Examples of R⁸ include those which are the same as for R⁴¹.

ma in formula (T1′) and m in formula (T1) are preferably 0 or 1, andmore preferably 0.

Examples of the ring represented by formula (T1′) and the ringrepresented by formula (T1) include the following rings. The bondingsite may be at any position.

It is preferable that the structural unit having a sultone ring has thefollowing groups. * in the following groups represents a bonding site.

It is preferable that the structural unit having an SO₂— group furtherhas a group derived from a polymerizable group. Examples of thepolymerizable group include a vinyl group, an acryloyl group, amethacryloyl group, an acryloyloxy group, a methacryloyloxy group, anacryloylamino group, a methacryloylamino group, an acryloylthio group, amethacryloylthio group and the like.

Particularly, the monomer from which the structural unit (a6) is derivedis preferably a monomer having an ethylenically unsaturated bond, andmore preferably a (meth)acrylic monomer.

The structural unit (a6) is preferably a structural unit represented byformula (Ix):

wherein, in formula (Ix), R^(x) represents an alkyl group having 1 to 6carbon atoms which may have a halogen atom, a hydrogen atom or a halogenatom,

-   -   A^(xx) represents an oxygen atom, —N(R^(c))— or a sulfur atom,    -   A^(x) represents a divalent saturated hydrocarbon group having 1        to 18 carbon atoms, and —CH₂— included in the saturated        hydrocarbon group may be replaced by —O—, —CO— or —N(R^(d))—,    -   X¹¹ represents an oxygen atom, a sulfur atom or a methylene        group,    -   R⁴¹ represents an alkyl group having 1 to 12 carbon atoms which        may have a halogen atom or a hydroxy group, a halogen atom, a        hydroxy group, a cyano group, an alkoxy group having 1 to 12        carbon atoms, an aryl group having 6 to 12 carbon atoms, an        aralkyl group having 7 to 12 carbon atoms, a glycidyloxy group,        an alkoxycarbonyl group having 2 to 12 carbon atoms, or an        alkylcarbonyl group having 2 to 4 carbon atoms,    -   ma represents an integer of 0 to 9, and when ma is 2 or more, a        plurality of R⁴¹ may be the same or different, and    -   R^(c) and R^(d) each independently represent a hydrogen atom or        an alkyl group having 1 to 6 carbon atoms.

Examples of the halogen atom as for R^(x) include a fluorine atom, achlorine atom, a bromine atom and an iodine atom.

Examples of the alkyl group as for R^(x) include a methyl group, anethyl group, an n-propyl group, an isopropyl group, an n-butyl group, asec-butyl group, a tert-butyl group, an n-pentyl group and an n-hexylgroup, and an alkyl group having 1 to 4 carbon atoms is preferable, anda methyl group or an ethyl group is more preferable.

Examples of the alkyl group having a halogen atom as for R^(x) include atrifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group,a perfluoroisopropyl group, a perfluorobutyl group, a perfluorosec-butylgroup, a perfluorotert-butyl group, a perfluoropentyl group, aperfluorohexyl group, a trichloromethyl group, a tribromomethyl groupand a triiodomethyl group.

R^(x) is preferably a hydrogen atom or an alkyl group having 1 to 4carbon atoms, more preferably a hydrogen atom, a methyl group or anethyl group, and still more preferably a hydrogen atom or a methylgroup.

Examples of the divalent saturated hydrocarbon group as for A^(x)include a linear alkanediyl group, a branched alkanediyl group and amonocyclic or polycyclic divalent alicyclic saturated hydrocarbon group,and the divalent saturated hydrocarbon group may be those obtained bycombining two or more of these groups.

Specific examples thereof include linear alkanediyl groups such as amethylene group, an ethylene group, a propane-1,3-diyl group, apropane-1,2-diyl group, a butane-1,4-diyl group, a pentane-1,5-diylgroup, a hexane-1,6-diyl group, a heptane-1,7-diyl group, anoctane-1,8-diyl group, a nonane-1,9-diyl group, a decane-1,10-diylgroup, an undecane-1,11-diyl group, a dodecane-1,12-diyl group, atridecane-1,13-diyl group, a tetradecane-1,14-diyl group, apentadecane-1,15-diyl group, a hexadecane-1,16-diyl group, aheptadecane-1,17-diyl group, an ethane-1,1-diyl group, apropane-1,1-diyl group and a propane-2,2-diyl group;

-   -   branched alkanediyl groups such as a butane-1,3-diyl group, a        2-methylpropane-1,3-diyl group, a 2-methylpropane-1,2-diyl        group, a pentane-1,4-diyl group and a 2-methylbutane-1,4-diyl        group;    -   monocyclic divalent alicyclic saturated hydrocarbon groups which        are cycloalkanediyl groups such as a cyclobutane-1,3-diyl group,        a cyclopentane-1,3-diyl group, a cyclohexane-1,4-diyl group and        a cyclooctane-1,5-diyl group; and    -   polycyclic divalent alicyclic saturated hydrocarbon groups such        as a norbornane-1,4-diyl group, a norbornane-2,5-diyl group, an        adamantane-1,5-diyl group and an adamantane-2,6-diyl group.

Examples of R⁴¹, X¹¹ and ma include those which are the same as informula (T1′).

Examples of the sultone ring include those mentioned above, and ofthese, preferred are the above-mentioned rings in which the bonding siteis specified.

Examples of the structural unit (a6) include the following structuralunits.

Of these, structural units represented by formula (a6-1), formula(a6-2), formula (a6-6), formula (a6-7), formula (a6-8) and formula(a6-12) are preferable, and structural units represented by formula(a6-1), formula (a6-2), formula (a6-7) and (a6-8) are more preferable.

When the resin (A) includes the structural unit (a6), the content ispreferably 1 to 50 mol %, more preferably 2 to 40 mol %, and still morepreferably 3 to 30 mol %, based on all structural units of the resin(A).

<Structural Unit (II)>

The resin (A) may further include a structural unit which is decomposedupon exposure to radiation to generate an acid (hereinafter sometimesreferred to as “structural unit (II)”). Specific examples of thestructural unit (II) include the structural units mentioned in JP2016-79235 A, and a structural unit having a sulfonate group or acarboxylate group and an organic cation in a side chain or a structuralunit having a sulfonio group and an organic anion in a side chain arepreferable.

The structural unit having a sulfonate group or a carboxylate group andan organic cation in a side chain is preferably a structural unitrepresented by formula (II-2-A′):

wherein, in formula (II-2-A′),

-   -   X^(III3) represents a divalent saturated hydrocarbon group        having 1 to 18 carbon atoms, —CH₂— included in the saturated        hydrocarbon group may be replaced by —O—, —S— or —CO—, and a        hydrogen atom included in the saturated hydrocarbon group may be        substituted with a halogen atom, an alkyl group having 1 to 6        carbon atoms which may have a halogen atom, or a hydroxy group,    -   A^(x1) represents an alkanediyl group having 1 to 8 carbon        atoms, and a hydrogen atom included in the alkanediyl group may        be substituted with a fluorine atom or a perfluoroalkyl group        having 1 to 6 carbon atoms,    -   RA⁻ represents a sulfonate group or a carboxylate group,    -   R^(III3) represents a hydrogen atom, a halogen atom, or an alkyl        group having 1 to 6 carbon atoms which may have a halogen atom,        and    -   ZA⁺ represents an organic cation.

Examples of the halogen atom represented by R^(III3) include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom.

Examples of the alkyl group having 1 to 6 carbon atoms which may have ahalogen atom represented by R^(III3) include those which are the same asthe alkyl group having 1 to 6 carbon atoms which may have a halogen atomrepresented by R^(a8).

Examples of the alkanediyl group having 1 to 8 carbon atoms representedby A^(x1) include a methylene group, an ethylene group, apropane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diylgroup, a hexane-1,6-diyl group, an ethane-1,1-diyl group, apropane-1,1-diyl group, a propane-1,2-diyl group, a propane-2,2-diylgroup, a pentane-2,4-diyl group, a 2-methylpropane-1,3-diyl group, a2-methylpropane-1,2-diyl group, a pentane-1,4-diyl group, a2-methylbutane-1,4-diyl group and the like.

Examples of the perfluoroalkyl group having 1 to 6 carbon atoms whichmay be substituted in A^(x1) include a trifluoromethyl group, aperfluoroethyl group, a perfluoropropyl group, a perfluoroisopropylgroup, a perfluorobutyl group, a perfluorosec-butyl group, aperfluorotert-butyl group, a perfluoropentyl group, a perfluorohexylgroup and the like.

Examples of the divalent saturated hydrocarbon group having 1 to 18carbon atoms represented by X^(III3) include a linear or branchedalkanediyl group, a monocyclic or a polycyclic divalent alicyclicsaturated hydrocarbon group, or a combination thereof.

Specific examples thereof include linear alkanediyl groups such as amethylene group, an ethylene group, a propane-1,3-diyl group, apropane-1,2-diyl group, a butane-1,4-diyl group, a pentane-1,5-diylgroup, a hexane-1,6-diyl group, a heptane-1,7-diyl group, anoctane-1,8-diyl group, a nonane-1,9-diyl group, a decane-1,10-diylgroup, an undecane-1,11-diyl group and a dodecane-1,12-diyl group;branched alkanediyl groups such as a butane-1,3-diyl group, a2-methylpropane-1,3-diyl group, a 2-methylpropane-1,2-diyl group, apentane-1,4-diyl group and a 2-methylbutane-1,4-diyl group;cycloalkanediyl groups such as a cyclobutane-1,3-diyl group, acyclopentane-1,3-diyl group, a cyclohexane-1,4-diyl group and acyclooctane-1,5-diyl group; and divalent polycyclic alicyclic saturatedhydrocarbon groups such as a norbornane-1,4-diyl group, anorbornane-2,5-diyl group, an adamantane-1,5-diyl group and anadamantane-2,6-diyl group.

Those in which —CH₂— included in the saturated hydrocarbon group arereplaced by —O—, —S— or —CO— include, for example, divalent groupsrepresented by formula (X1) to formula (X53). Before replacing —CH₂—included in the saturated hydrocarbon group by —O—, —S— or —CO—, thenumber of carbon atoms is 17 or less. In the following formulas, * and** represent a bonding site, and * represents a bonding site to A^(x1).

X³ represents a divalent saturated hydrocarbon group having 1 to 16carbon atoms.

X⁴ represents a divalent saturated hydrocarbon group having 1 to 15carbon atoms.

X⁵ represents a divalent saturated hydrocarbon group having 1 to 13carbon atoms.

X⁶ represents a divalent saturated hydrocarbon group having 1 to 14carbon atoms.

X⁷ represents a trivalent saturated hydrocarbon group having 1 to 14carbon atoms.

X⁸ represents a divalent saturated hydrocarbon group having 1 to 13carbon atoms.

Examples of ZA⁺ in formula (II-2-A′) include those which are the same asthe cation Z1+ in the salt represented by formula (B1).

The structural unit represented by formula (II-2-A′) is preferably astructural unit represented by formula (II-2-A):

wherein, in formula (II-2-A), R^(III3), X^(III3) and ZA⁺ are the same asdefined above,

-   -   z2A represents an integer of 0 to 6,    -   R^(III2) and R^(III4) each independently represent a hydrogen        atom, a fluorine atom or a perfluoroalkyl group having 1 to 6        carbon atoms, and when z2A is 2 or more, a plurality of R^(III2)        and R^(III4) may be the same or different form each other, and    -   Q^(a) and Q^(b) each independently represent a fluorine atom or        a perfluoroalkyl group having 1 to 6 carbon atoms.

Examples of the perfluoroalkyl group having 1 to 6 carbon atomsrepresented by R^(III2), R^(III4), Q^(a) and Q^(b) include those whichare the same as the perfluoroalkyl group having 1 to 6 carbon atomsrepresented by Q^(b1) mentioned above.

The structural unit represented by formula (II-2-A) is preferably astructural unit represented by formula (II-2-A-1):

wherein, in formula (II-2-A-1),

-   -   R^(III2), R^(III3), R^(III4), Q^(a), Q^(b) and ZA⁺ are the same        as defined above,    -   R^(III5) represents a saturated hydrocarbon group having 1 to 12        carbon atoms,    -   z2A1 represents an integer of 0 to 6, and    -   X^(I2) represents a divalent saturated hydrocarbon group having        1 to 11 carbon atoms, —CH₂— included in the saturated        hydrocarbon group may be replaced by —O—, —S— or —CO—, and a        hydrogen atom included in the saturated hydrocarbon group may be        substituted with a halogen atom or a hydroxy group.

Examples of the saturated hydrocarbon group having 1 to 12 carbon atomsrepresented by R^(III5) include linear or branched alkyl groups such asa methyl group, an ethyl group, a propyl group, an isopropyl group, abutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, ahexyl group, a heptyl group, an octyl group, a nonyl group, a decylgroup, an undecyl group and a dodecyl group.

Examples of the divalent saturated hydrocarbon group represented byX^(I2) include those which are the same as the divalent saturatedhydrocarbon group represented by X^(III3).

The structural unit represented by formula (II-2-A-1) is more preferablya structural unit represented by formula (II-2-A-2):

wherein, in formula (II-2-A-2), R^(III3), R^(III5) and ZA⁺ are the sameas defined above, and

-   -   m and nA each independently represent 1 or 2.

The structural unit represented by formula (II-2-A′) includes, forexample, the following structural units, structural units in which agroup corresponding to a methyl group of R^(III3) is substituted with analkyl group having 1 to 6 carbon atoms which may have a hydrogen atom, ahalogen atom (e.g., fluorine atom) or a halogen atom (e.g.,trifluoromethyl group, etc.) and the structural units mentioned in WO2012/050015 A. ZA⁺ represents an organic cation.

The structural unit having a sulfonio group and an organic anion in aside chain is preferably a structural unit represented by formula(II-1-1):

wherein, in formula (II-1-1),

-   -   A^(II1) represents a single bond or a divalent linking group,    -   R^(II1) represents a divalent aromatic hydrocarbon group having        6 to 18 carbon atoms,    -   R^(II2) and R^(II3) each independently represent a hydrocarbon        group having 1 to 18 carbon atoms, and R^(II2) and R^(II3) may        be bonded to each other to form a ring together with sulfur        atoms to which R^(II2) and R^(II3) are bonded,    -   R^(II4) represents a hydrogen atom, a halogen atom, or an alkyl        group having 1 to 6 carbon atoms which may have a halogen atom,        and    -   A⁻ represents an organic anion.

Examples of the divalent aromatic hydrocarbon group having 6 to 18carbon atoms represented by R^(II1) include a phenylene group and anaphthylene group.

Examples of the hydrocarbon group represented by R^(II2) and R^(II3)include an alkyl group, an alicyclic hydrocarbon group, an aromatichydrocarbon group, and groups obtained by combining these groups.

Examples of the alkyl group and the alicyclic hydrocarbon group includethose which are the same as mentioned above.

Examples of the aromatic hydrocarbon group include aryl groups such as aphenyl group, a naphthyl group, an anthryl group, a biphenyl group and aphenanthryl group.

Examples of the combined group include groups obtained by combining theabove-mentioned alkyl group and alicyclic hydrocarbon group, aralkylgroups such as a benzyl group, aromatic hydrocarbon groups having analkyl group (a p-methylphenyl group, a p-tert-butylphenyl group, a tolylgroup, a xylyl group, a cumenyl group, a mesityl group, a2,6-diethylphenyl group, a 2-methyl-6-ethylphenyl group, etc.), aromatichydrocarbon groups having an alicyclic hydrocarbon group (ap-cyclohexylphenyl group, a p-adamantylphenyl group, etc.),aryl-cycloalkyl groups such as a phenylcyclohexyl group, and the like.Examples of the halogen atom represented by R^(II4) include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom.

Examples of the alkyl group having 1 to 6 carbon atoms which may have ahalogen atom represented by R^(II4) include those which are the same asthe alkyl group having 1 to 6 carbon atoms which may have a halogen atomrepresented by R^(a8).

Examples of the divalent linking group represented by A^(II1) include adivalent saturated hydrocarbon group having 1 to 18 carbon atoms, and—CH₂— included in the divalent saturated hydrocarbon group may bereplaced by —O—, —S— or —CO—. Specific examples thereof include thosewhich are the same as the divalent saturated hydrocarbon group having 1to 18 carbon atoms represented by X^(III3).

Examples of the structural unit including a cation in formula (II-1-1)include the following structural units and structural units in which agroup corresponding to a methyl group of R^(II4) is substituted with ahydrogen atom, a halogen atom (e.g., a fluorine atom, etc.) or an alkylgroup having 1 to 6 carbon atoms which may have a halogen atom (e.g., atrifluoromethyl group, etc.) and the like.

Examples of the organic anion represented by A⁻ include a sulfonic acidanion, a sulfonylimide anion, a sulfonylmethide anion and a carboxylicacid anion. The organic anion represented by A⁻ is preferably a sulfonicacid anion, and the sulfonic acid anion is more preferably an anionincluded in the above-mentioned salt represented by formula (B1). Thesulfonylimide anion, the sulfonylmethide anion and the carboxylic acidanion are more preferably an anion AI⁻ included in the above-mentionedsalt represented by formula (I).

Examples of the structural unit represented by formula (II-1-1) includethe followings.

When the structural unit (II) is included in the resin (A), the contentof the structural unit (II) is preferably 1 to 20 mol %, more preferably2 to 15 mol %, and still more preferably 3 to 10 mol %, based on allstructural units of the resin (A).

The resin (A) may include structural units other than the structuralunits mentioned above, and examples of such structural unit includestructural units well-known in the art.

The resin (A) is preferably a resin composed of a structural unit (a1)and a structural unit (s), namely, a copolymer of a monomer (a1) and amonomer (s).

The structural unit (a1) is preferably at least one selected from thegroup consisting of a structural unit (a1-0), a structural unit (a1-1)and a structural unit (a1-2) (preferably the structural unit having acyclohexyl group or a cyclopentyl group), more preferably at least two,and still more preferably at least two selected from the groupconsisting of a structural unit (a1-1) and a structural unit (a1-2).

The structural unit (s) is preferably at least one selected from thegroup consisting of a structural unit (a2) and a structural unit (a3).The structural unit (a2) is preferably a structural unit (a2-1) or astructural unit (a2-A). The structural unit (a3) is preferably at leastone selected from the group consisting of a structural unit representedby formula (a3-1), a structural unit represented by formula (a3-2) and astructural unit represented by formula (a3-4).

The respective structural units constituting the resin (A) may be usedalone, or two or more structural units may be used in combination. Usinga monomer from which these structural units are derived, it is possibleto produce by a known polymerization method (e.g. radical polymerizationmethod). The content of the respective structural units included in theresin (A) can be adjusted according to the amount of the monomer used inthe polymerization.

The weight-average molecular weight of the resin (A) is preferably 2,000or more (more preferably 2,500 or more, and still more preferably 3,000or more), and 50,000 or less (more preferably 30,000 or less, and stillmore preferably 15,000 or less). In the present specification, theweight-average molecular weight is a value determined by gel permeationchromatography under the conditions mentioned in Examples.

<Resin Other than Resin (A)>

The resist composition of the present invention may use the resin otherthan the resin (A) in combination.

The resin other than the resin (A) includes, for example, a resinincluding a structural unit (a4) or a structural unit (a5) (hereinaftersometimes referred to as resin (X)).

The resin (X) is preferably a resin including a structural unit (a4),particularly.

In the resin (X), the content of the structural unit (a4) is preferably30 mol % or more, more preferably 40 mol % or more, and still morepreferably 45 mol % or more, based on the total of all structural unitsof the resin (X).

Examples of the structural unit, which may be further included in theresin (X), include a structural unit (a1), a structural unit (a2), astructural unit (a3) and structural units derived from other knownmonomers. Particularly, the resin (X) is preferably a resin composedonly of a structural unit (a4) and/or a structural unit (a5).

The respective structural unit constituting the resin (X) may be usedalone, or two or more structural units may be used in combination. Usinga monomer from which these structural units are derived, it is possibleto produce by a known polymerization method (e.g. radical polymerizationmethod). The content of the respective structural units included in theresin (X) can be adjusted according to the amount of the monomer used inthe polymerization.

The weight-average molecular weight of the resin (X) is preferably 6,000or more (more preferably 7,000 or more) and 80,000 or less (morepreferably 60,000 or less). The measurement means of the weight-averagemolecular weight of the resin (X) is the same as in the case of theresin (A).

When the resist composition of the present invention includes the resin(X), the content is preferably 1 to 60 parts by mass, more preferably 1to 50 parts by mass, still more preferably 1 to 40 parts by mass, yetmore preferably 1 to 30 parts by mass, and further preferably 1 to 8parts by mass, based on 100 parts by mass of the resin (A).

The content of the resin (A) in the resist composition is preferably 80%by mass or more and 99% by mass or less, and more preferably 90% by massor more and 99% by mass or less, based on the solid component of theresist composition. When including resins other than the resin (A), thetotal content of the resin (A) and resins other than the resin (A) ispreferably 80% by mass or more and 99% by mass or less, and morepreferably 90% by mass or more and 99% by mass or less, based on thesolid component of the resist composition. In the present specification,“solid content of resist composition” means the total of contents inwhich the below-mentioned solvent (E) is removed from the total amountof the resist composition. The solid content of the resist compositionand the content of the resin thereto can be measured by a known analysismeans such as liquid chromatography or gas chromatography.

<Solvent (E)>

The content of the solvent (E) in the resist composition is usually 90%by mass or more and 99.9% by mass or less, preferably 92% by mass ormore and 99% by mass or less, and more preferably 94% by mass or moreand 99% by mass or less. The content of the solvent (E) can be measured,for example, by a known analysis means such as liquid chromatography orgas chromatography.

Examples of the solvent (E) include glycol ether esters such asethylcellosolve acetate, methylcellosolve acetate and propylene glycolmonomethyl ether acetate; glycol ethers such as propylene glycolmonomethyl ether; esters such as ethyl lactate, butyl acetate, amylacetate and ethyl pyruvate; ketones such as acetone, methyl isobutylketone, 2-heptanone and cyclohexanone; and cyclic esters such asγ-butyrolactone. The solvent (E) may be used alone, or two or moresolvents may be used.

<Quencher (C)>

Examples of the quencher (C) include a basic nitrogen-containing organiccompound, and a salt generating an acid having an acidity lower thanthat of an acid generated from an acid generator. When the resistcomposition includes the quencher (C), the content of the quencher (C)is preferably about 0.01 to 15% by mass, more preferably about 0.01 to10% by mass, still more preferably about 0.1 to 8% by mass, and yet morepreferably about 0.1 to 7% by mass, based on the amount of the solidcomponent of the resist composition.

Examples of the basic nitrogen-containing organic compound include amineand an ammonium salt. Examples of the amine include an aliphatic amineand an aromatic amine. Examples of the aliphatic amine include a primaryamine, a secondary amine and a tertiary amine.

Examples of the amine include 1-naphthylamine, 2-naphthylamine, aniline,diisopropylaniline, 2-, 3- or 4-methylaniline, 4-nitroaniline,N-methylaniline, N,N-dimethylaniline, diphenylamine, hexylamine,heptylamine, octylamine, nonylamine, decylamine, dibutylamine,dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine,didecylamine, triethylamine, trimethylamine, tripropylamine,tributylamine, tripentylamine, trihexylamine, triheptylamine,trioctylamine, trinonylamine, tridecylamine, methyldibutylamine,methyldipentylamine, methyldihexylamine, methyldicyclohexylamine,methyldiheptylamine, methyldioctylamine, methyldinonylamine,methyldidecylamine, ethyldibutylamine, ethyldipentylamine,ethyldihexylamine, ethyldiheptylamine, ethyldioctylamine,ethyldinonylamine, ethyldidecylamine, dicyclohexylmethylamine,tris[2-(2-methoxyethoxy)ethyl]amine, triisopropanolamine,ethylenediamine, tetramethylenediamine, hexamethylenediamine,4,4′-diamino-1,2-diphenylethane,4,4′-diamino-3,3′-dimethyldiphenylmethane,4,4′-diamino-3,3′-diethyldiphenylmethane, 2,2′-methylenebisaniline,imidazole, 4-methylimidazole, pyridine, 4-methylpyridine,1,2-di(2-pyridyl)ethane, 1,2-di(4-pyridyl)ethane,1,2-di(2-pyridyl)ethene, 1,2-di(4-pyridyl)ethene,1,3-di(4-pyridyl)propane, 1,2-di(4-pyridyloxy)ethane,di(2-pyridyl)ketone, 4,4′-dipyridyl sulfide, 4,4′-dipyridyl disulfide,2,2′-dipyridylamine, 2,2′-dipicolylamine, bipyridine and the like,preferably diisopropylaniline, and more preferably2,6-diisopropylaniline.

Examples of the ammonium salt include tetramethylammonium hydroxide,tetraisopropylammonium hydroxide, tetrabutylammonium hydroxide,tetrahexylammonium hydroxide, tetraoctylammonium hydroxide,phenyltrimethylammonium hydroxide,3-(trifluoromethyl)phenyltrimethylammonium hydroxide,tetra-n-butylammonium salicylate and choline.

The acidity in a salt generating an acid having an acidity lower thanthat of an acid generated from the acid generator is indicated by theacid dissociation constant (pKa). Regarding the salt generating an acidhaving an acidity lower than that of an acid generated from the acidgenerator, the acid dissociation constant of an acid generated from thesalt usually meets the following inequality: −3<pKa, preferably−1<pKa<7, and more preferably 0<pKa<5.

Examples of the salt generating an acid having an acidity lower thanthat of an acid generated from the acid generator include saltsrepresented by the following formulas, a salt represented by formula (D)mentioned in JP 2015-147926 A (hereinafter sometimes referred to as“weak acid inner salt (D)”), and salts mentioned in JP 2012-229206 A, JP2012-6908 A, JP 2012-72109 A, JP 2011-39502 A and JP 2011-191745 A. Thesalt generating an acid having an acidity lower than that of an acidgenerated from the acid generator is preferably a salt generating acarboxylic acid having an acidity lower than that of an acid generatedfrom the acid generator (salt having a carboxylic acid anion), morepreferably a weak acid inner salt (D), and still more preferably adiphenyliodonium salt containing a phenyl group substituted with acarboxylic acid anion among the weak acid inner salt (D).

Examples of the weak acid inner salt (D) is preferably adiphenyliodonium salt having an iodonium cation to which two phenylgroups are bonded, and a carboxylic acid anion substituted with at leastone phenyl group of two phenyl groups bonded to the iodonium cation, andspecific examples thereof include a salt represented by the followingformula:

wherein, in formula (D),

-   -   R^(D1) and R^(D2) each independently represent a hydrocarbon        group having 1 to 12 carbon atoms, an alkoxy group having 1 to 6        carbon atoms, an acyl group having 2 to 7 carbon atoms, an        acyloxy group having 2 to 7 carbon atoms, an alkoxycarbonyl        group having 2 to 7 carbon atoms, a nitro group or a halogen        atom, and    -   m′ and n′ each independently represent an integer of 0 to 4, and        when m′ is 2 or more, a plurality of R^(D1) may be the same or        different, and when n′ is 2 or more, a plurality of R^(D2) may        be the same or different.

Examples of the hydrocarbon group as for R^(D1) and R^(D2) include achain hydrocarbon group, an alicyclic hydrocarbon group, an aromatichydrocarbon group, and a group formed by combining these groups.

Examples of the chain hydrocarbon group include alkyl groups such as amethyl group, an ethyl group, a propyl group, an isopropyl group, abutyl group, an isobutyl group, a tert-butyl group, a pentyl group, ahexyl group, a nonyl group and the like.

The alicyclic hydrocarbon group may be either monocyclic or polycyclic,or may be either saturated or unsaturated. Examples thereof includecycloalkyl groups such as a cyclopropyl group, a cyclobutyl group, acyclopentyl group, a cyclohexyl group, a cyclononyl group and acyclododecyl group, a norbornyl group, an adamantyl group and the like.

Examples of the aromatic hydrocarbon group include aryl groups such as aphenyl group, a 1-naphthyl group, a 2-naphthyl group, a 2-methylphenylgroup, a 3-methylphenyl group, a 4-methylphenyl group, a 4-ethylphenylgroup, a 4-propylphenyl group, a 4-isopropylphenyl group, a4-butylphenyl group, a 4-t-butylphenyl group, a 4-hexylphenyl group, a4-cyclohexylphenyl group, an anthryl group, a p-adamantylphenyl group, atolyl group, a xylyl group, a cumenyl group, a mesityl group, a biphenylgroup, a phenanthryl group, a 2,6-diethylphenyl group, a2-methyl-6-ethylphenyl group and the like.

Examples of the group formed by combining these groups include analkyl-cycloalkyl group, a cycloalkyl-alkyl group, an aralkyl group(e.g., a phenylmethyl group, a 1-phenylethyl group, a 2-phenylethylgroup, a 1-phenyl-1-propyl group, a 1-phenyl-2-propyl group, a2-phenyl-2-propyl group, a 3-phenyl-1-propyl group, a 4-phenyl-1-butylgroup, a 5-phenyl-1-pentyl group, a 6-phenyl-1-hexyl group, etc.) andthe like.

Examples of the alkoxy group include a methoxy group, an ethoxy groupand the like.

Examples of the acyl group include an acetyl group, a propanoyl group, abenzoyl group, a cyclohexanecarbonyl group and the like.

Examples of the acyloxy group include a group obtained by bonding an oxygroup (—O—) to the above acyl group.

Examples of the alkoxycarbonyl group include a group obtained by bondinga carbonyl group (—CO—) to the above alkoxy group.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and the like.

Preferably, R^(D1) and R^(D2) each independently represent an alkylgroup having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 10carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an acyl grouphaving 2 to 4 carbon atoms, an acyloxy group having 2 to 4 carbon atoms,an alkoxycarbonyl group having 2 to 4 carbon atoms, a nitro group or ahalogen atom.

Preferably, m′ and n′ are each independently an integer of 0 to 2, andmore preferably 0, and when m′ is 2 or more, a plurality of R^(D)1 maybe the same or different, and when n′ is 2 or more, a plurality ofR^(D2) may be the same or different.

More specifically, the following salts are exemplified.

<Other Components>

The resist composition of the present invention may also includecomponents other than the components mentioned above (hereinaftersometimes referred to as “other components (F)”). The other components(F) are not particularly limited and it is possible to use variousadditives known in the resist field, for example, sensitizers,dissolution inhibitors, surfactants, stabilizers and dyes.

<Preparation of Resist Composition>

The resist composition of the present invention can be prepared bymixing a salt (I) and a resin (A), and if necessary, an acid generator(B), resins other than the resin (A), a solvent (E), a quencher (C) andother components (F). The order of mixing these components is any orderand is not particularly limited. It is possible to select, as thetemperature during mixing, appropriate temperature from 10 to 40° C.,according to the type of the resin, the solubility in the solvent (E) ofthe resin and the like. It is possible to select, as the mixing time,appropriate time from 0.5 to 24 hours according to the mixingtemperature. The mixing means is not particularly limited and it ispossible to use mixing with stirring.

After mixing the respective components, the mixture is preferablyfiltered through a filter having a pore diameter of about 0.003 to 0.2μm.

(Method for Producing Resist Pattern)

The method for producing a resist pattern of the present inventioninclude:

-   -   (1) a step of applying the resist composition of the present        invention on a substrate,    -   (2) a step of drying the applied composition to form a        composition layer,    -   (3) a step of exposing the composition layer,    -   (4) a step of heating the exposed composition layer, and    -   (5) a step of developing the heated composition layer.

The resist composition can be usually applied on a substrate using aconventionally used apparatus, such as a spin coater. Examples of thesubstrate include inorganic substrates such as a silicon wafer, andorganic substrates in which a resist film is formed on the surface.Before applying the resist composition, the substrate may be washed, andan organic antireflection film may be formed on the substrate.

The solvent is removed by drying the applied composition to form acomposition layer. Drying is performed by evaporating the solvent usinga heating device such as a hot plate (so-called “prebake”), or adecompression device. The heating temperature is preferably 50 to 200°C. and the heating time is preferably 10 to 180 seconds. The pressureduring drying under reduced pressure is preferably about 1 to 1.0×10⁵Pa.

The composition layer thus obtained is usually exposed using an aligner.The aligner may be a liquid immersion aligner. It is possible to use, asan exposure source, various exposure sources, for example, exposuresources capable of emitting laser beam in an ultraviolet region such asKrF excimer laser (wavelength of 248 nm), ArF excimer laser (wavelengthof 193 nm) and F2 excimer laser (wavelength of 157 nm), an exposuresource capable of emitting harmonic laser beam in a far-ultraviolet orvacuum ultra violet region by wavelength-converting laser beam from asolid-state laser source (YAG or semiconductor laser), an exposuresource capable of emitting electron beam or extreme ultraviolet light(EUV) and the like. In the present specification, such exposure toradiation is sometimes collectively referred to as “exposure”. Theexposure is usually performed through a mask corresponding to a patternto be required. When electron beam is used as the exposure source,exposure may be performed by direct writing without using the mask.

The exposed composition layer is subjected to a heat treatment(so-called “post-exposure bake”) to promote the deprotection reaction inan acid-labile group. The heating temperature is usually about 50 to200° C., and preferably about 70 to 150° C. It is also possible toperform a chemical treatment (silylation) which adjusts thehydrophilicity or hydrophobicity of the resin on a surface side of thecomposition after heating. Before performing the development, the stepsof application of the resist composition, drying, exposure and heatingmay be repeatedly performed on the exposed composition layer.

The heated composition layer is usually developed with a developingsolution using a development apparatus. Examples of the developingmethod include a dipping method, a paddle method, a spraying method, adynamic dispensing method and the like. The developing temperature ispreferably, for example, 5 to 60° C. and the developing time ispreferably, for example, 5 to 300 seconds. It is possible to produce apositive resist pattern or negative resist pattern by selecting the typeof the developing solution as follows.

When the positive resist pattern is produced from the resist compositionof the present invention, an alkaline developing solution is used as thedeveloping solution. The alkaline developing solution may be variousaqueous alkaline solutions used in this field. Examples thereof includeaqueous solutions of tetramethylammonium hydroxide and(2-hydroxyethyl)trimethylammonium hydroxide (commonly known as choline).The surfactant may be contained in the alkaline developing solution.

It is preferable that the developed resist pattern is washed withultrapure water and then water remaining on the substrate and thepattern is removed.

When the negative resist pattern is produced from the resist compositionof the present invention, a developing solution containing an organicsolvent (hereinafter sometimes referred to as “organic developingsolution”) is used as the developing solution.

Examples of the organic solvent contained in the organic developingsolution include ketone solvents such as 2-hexanone and 2-heptanone;glycol ether ester solvents such as propylene glycol monomethyl etheracetate; ester solvents such as butyl acetate; glycol ether solventssuch as propylene glycol monomethyl ether; amide solvents such asN,N-dimethylacetamide; and aromatic hydrocarbon solvents such asanisole.

The content of the organic solvent in the organic developing solution ispreferably 90% by mass or more and 100% by mass or less, more preferably95% by mass or more and 100% by mass or less, and still more preferablythe organic developing solution is substantially composed of the organicsolvent.

Particularly, the organic developing solution is preferably a developingsolution containing butyl acetate and/or 2-heptanone. The total contentof butyl acetate and 2-heptanone in the organic developing solution ispreferably 50% by mass or more and 100% by mass or less, more preferably90% by mass or more and 100% by mass or less, and still more preferablythe organic developing solution is substantially composed of butylacetate and/or 2-heptanone.

The surfactant may be contained in the organic developing solution. Atrace amount of water may be contained in the organic developingsolution.

During development, the development may be stopped by replacing by asolvent with the type different from that of the organic developingsolution.

The developed resist pattern is preferably washed with a rinsingsolution. The rinsing solution is not particularly limited as long as itdoes not dissolve the resist pattern, and it is possible to use asolution containing an ordinary organic solvent which is preferably analcohol solvent or an ester solvent.

After washing, the rinsing solution remaining on the substrate and thepattern is preferably removed.

<Applications>

The resist composition of the present invention is suitable as a resistcomposition for exposure of KrF excimer laser, a resist composition forexposure of ArF excimer laser, a resist composition for exposure ofelectron beam (EB) or a resist composition for exposure of EUV,particularly a resist composition for exposure of electron beam (EB) ora resist composition for exposure of EUV, and the resist composition isuseful for fine processing of semiconductors.

EXAMPLES

The present invention will be described more specifically by way ofExamples. Percentages and parts expressing the contents or amounts usedin the Examples are by mass unless otherwise specified.

The weight-average molecular weight is a value determined by gelpermeation chromatography. Analysis conditions of gel permeationchromatography are as follows.

-   -   Column: TSKgel Multipore HXL-M×3+guardcolumn (manufactured by        TOSOH CORPORATION)    -   Eluent: tetrahydrofuran    -   Flow rate: 1.0 mL/min    -   Detector: RI detector    -   Column temperature: 40° C.    -   Injection amount: 100 μl    -   Molecular weight standards: polystyrene standard (manufactured        by TOSOH CORPORATION)

Structures of compounds were confirmed by measuring a molecular ion peakusing mass spectrometry (Liquid Chromatography: Model 1100, manufacturedby Agilent Technologies, Inc., and Mass Spectrometry: Model LC/MSD,manufactured by Agilent Technologies, Inc.). The value of this molecularion peak in the following Examples is indicated by “MASS”.

Example 1: Synthesis of Salt Represented by Formula (I-1224)

22.55 Parts of a compound represented by formula (I-1224-a), 4.56 partsof a compound represented by formula (I-1224-c), 150 parts of ethylacetate and 15 parts of tetrahydrofuran were mixed, followed by stirringat 23° C. for 30 minutes. To the mixed solution thus obtained, 13.10parts of a compound represented by formula (I-1224-b) was added,followed by stirring at 23° C. for 18 hours. To the reaction mass thusobtained, 50 parts of n-heptane and 70 parts of ion-exchanged water wereadded, and after stirring at 23° C. for 30 minutes, the organic layerwas isolated through separation. To the organic layer thus recovered, 70parts of ion-exchanged water was added, and after stirring at 23° C. for30 minutes, the organic layer was isolated through separation. Thiswater washing operation was repeated four times. The organic layer thusobtained was concentrated and then the concentrated mass was isolatedusing a column (silica gel 60N (spherical, neutral) 100-210 μm;manufactured by Kanto Chemical Co., Inc., developing solvent:n-heptane/ethyl acetate=1/1) to obtain 8.91 parts of a compoundrepresented by formula (I-1224-d).

1.02 Parts of a compound represented by formula (I-1224-d) and 10 partsof tetrahydrofuran were mixed, and after stirring at 23° C. for 30minutes and cooling to 5° C., 0.14 part of sodium hydride was added. Tothe mixture thus obtained, 1.82 parts of a salt represented by formula(I-1224-e) was added, followed by stirring at 5° C. for 3 hours andfurther stirring at 23° C. for 1 hour. To the mixture thus obtained, 30parts of chloroform and 15 parts of ion-exchanged water were added, andafter stirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. The organic layer thus obtained was concentrated and30 parts of tert-butyl methyl ether was added to the concentratedresidue. After stirring at 23° C. for 30 minutes, the supernatant wasremoved, followed by concentration to obtain 1.95 parts of a saltrepresented by formula (I-1224-f).

0.78 Part of a salt represented by formula (I-1224-f), 1.02 parts of asalt represented by formula (I-8-g), 30 parts of chloroform and 15 partsof ethyl acetate were mixed, followed by stirring at 23° C. for 2 hours.To the mixture thus obtained, 20 parts of ion-exchanged water was added,and after stirring at 23° C. for 30 minutes, the organic layer wasisolated through separation. This water washing operation was repeatedfive times. The organic layer thus obtained was concentrated and 30parts of tert-butyl methyl ether was added to the concentrated residue,followed by stirring at 23° C. for 30 minutes and further filtration toobtain 1.21 parts of a salt represented by formula (I-1224).

MASS (ESI (+) Spectrum): M⁺ 457.2

MASS (ESI (−) Spectrum): M⁻ 517.1

Example 2: Synthesis of Salt Represented by Formula (I-1232)

0.78 Part of a salt represented by formula (I-1224-f), 0.91 part of asalt represented by formula (I-16-g), 30 parts of chloroform and 15parts of ethyl acetate were mixed, followed by stirring at 23° C. for 2hours. To the mixture thus obtained, 20 parts of ion-exchanged water wasadded, and after stirring at 23° C. for 30 minutes, the organic layerwas isolated through separation. This water washing operation wasrepeated five times. The organic layer thus obtained was concentratedand 30 parts of tert-butyl methyl ether was added to the concentratedresidue, followed by stirring at 23° C. for 30 minutes and furtherfiltration to obtain 1.23 parts of a salt represented by formula(I-1232).

MASS (ESI (+) Spectrum): M⁺ 457.2

MASS (ESI (−) Spectrum): M⁻ 467.1

Example 3: Synthesis of Salt Represented by Formula (I-8)

1.02 Parts of a compound represented by formula (I-1224-d) and 10 partsof tetrahydrofuran were mixed, and after stirring at 23° C. for 30minutes and further cooling to 5° C., 0.14 part of sodium hydride wasadded. To the mixture thus obtained, 1.82 parts of a salt represented byformula (I-1224-e) was added, followed by stirring at 5° C. for 3 hours.To the mixture thus obtained, 6.30 parts of 1N hydrochloric acid wasadded, followed by raising the temperature to 23° C. and furtherstirring at 23° C. for 6 hours. To the mixture thus obtained, 30 partsof chloroform and 15 parts of ion-exchanged water were added, and afterstirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. The organic layer thus obtained was concentrated,and 1 part of acetonitrile and 30 parts of tert-butyl methyl ether wereadded to the concentrated residue. After stirring at 23° C. for 30minutes, the supernatant was removed, followed by concentration toobtain 1.55 parts of a salt represented by formula (I-8-f).

0.79 Part of a salt represented by formula (I-8-f), 1.20 parts of a saltrepresented by formula (I-8-g) and 20 parts of chloroform were added,followed by stirring at 23° C. for 3 hours. To the reaction product thusobtained, 15 parts of ion-exchanged water was added, and after stirringat 23° C. for 30 minutes, the organic layer was isolated throughseparation. To the organic layer thus obtained, 15 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated five times. The organic layer thusobtained was concentrated, and 1.5 parts of acetonitrile and 30 parts oftert-butyl methyl ether were added to the concentrated residue. Afterstirring at 23° C. for 30 minutes, the supernatant was removed, followedby concentration to obtain 1.25 parts of a salt represented by formula(I-8).

MASS (ESI (+) Spectrum): M⁺ 385.1

MASS (ESI (−) Spectrum): M⁻ 517.1

Example 4: Synthesis of Salt Represented by Formula (I-16)

0.79 Part of a salt represented by formula (I-8-f), 1.07 parts of a saltrepresented by formula (I-16-g) and 20 parts of chloroform were added,followed by stirring at 23° C. for 3 hours. To the reaction product thusobtained, 15 parts of ion-exchanged water was added, and after stirringat 23° C. for 30 minutes, the organic layer was isolated throughseparation. To the organic layer thus obtained, 15 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated five times. The organic layer thusobtained was concentrated, and 1.5 parts of acetonitrile and 30 parts oftert-butyl methyl ether were added to the concentrated residue. Afterstirring at 23° C. for 30 minutes, the supernatant was removed, followedby concentration to obtain 1.29 parts of a salt represented by formula(I-16).

MASS (ESI (+) Spectrum): M⁺ 385.1 MASS (ESI (−) Spectrum): M⁻ 467.1

Example 5: Synthesis of Salt Represented by Formula (I-160)

0.98 Part of a salt represented by formula (I-8-f) and 30 parts ofdimethylformamide were mixed, and after stirring at 23° C. for 30minutes, 0.16 part of potassium carbonate and 0.05 part of potassiumiodide were added and the temperature was raised to 75° C. To themixture thus obtained, 1.13 parts of a compound represented by formula(I-160-a) was added, followed by stirring at 75° C. for 5 hours andfurther cooling to 23° C. To the mixture thus obtained, 50 parts ofchloroform and 20 parts of an aqueous 5% oxalic acid solution wereadded, and after stirring at 23° C. for 30 minutes, the organic layerwas isolated through separation. To the organic layer thus obtained, 20parts of ion-exchanged water was added, and after stirring at 23° C. for30 minutes, the organic layer was isolated through separation. Thiswater washing operation was repeated five times. The organic layer thusobtained was concentrated to obtain 1.31 parts of a salt represented byformula (I-160-b).

1.00 Part of a salt represented by formula (I-160-b), 1.02 parts of asalt represented by formula (I-8-g), 30 parts of chloroform and 15 partsof ethyl acetate were mixed, followed by stirring at 23° C. for 2 hours.To the mixture thus obtained, 20 parts of ion-exchanged water was added,and after stirring at 23° C. for 30 minutes, the organic layer wasisolated through separation. This water washing operation was repeatedfive times. The organic layer thus obtained was concentrated and 30parts of tert-butyl methyl ether was added to the concentrated residue,followed by stirring at 23° C. for 30 minutes and further filtration toobtain 1.36 parts of a salt represented by formula (I-160).

MASS (ESI (+) Spectrum): M⁺ 591.3

MASS (ESI (−) Spectrum): M⁻ 517.1

Example 6: Synthesis of Salt Represented by Formula (I-168)

1.00 Part of a salt represented by formula (I-160-b), 0.91 part of asalt represented by formula (I-16-g), 30 parts of chloroform and 15parts of ethyl acetate were mixed, followed by stirring at 2300 for 2hours. To the mixture thus obtained, 20 parts of ion-exchanged water wasadded, and after stirring at 23° C. for 30 minutes, the organic layerwas isolated through separation. This water washing operation wasrepeated five times. The organic layer thus obtained was concentratedand 30 parts of tert-butyl methyl ether was added to the concentratedresidue, followed by stirring at 23° C. for 30 minutes and furtherfiltration to obtain 1.29 parts of a salt represented by formula(I-168).

MASS (ESI (+) Spectrum): M⁺ 591.3

MASS (ESI (−) Spectrum): M⁻ 467.1

Example 7: Synthesis of Salt Represented by Formula (I-156)

1.00 Part of a salt represented by formula (I-160-b), 0.66 part of asalt represented by formula (I-4-g), 30 parts of chloroform and 15 partsof ethyl acetate were mixed, followed by stirring at 23° C. for 2 hours.To the mixture thus obtained, 20 parts of ion-exchanged water was added,and after stirring at 23° C. for 30 minutes, the organic layer wasisolated through separation. This water washing operation was repeatedfive times. The organic layer thus obtained was concentrated, and 1 partof acetonitrile and 30 parts of tert-butyl methyl ether were added tothe concentrated residue. After stirring at 23° C. for 30 minutes, thesupernatant was removed, followed by concentration to obtain 1.03 partsof a salt represented by formula (I-156).

MASS (ESI (+) Spectrum): M⁺ 591.3

MASS (ESI (−) Spectrum): M⁻ 311.0

Example 8: Synthesis of Salt Represented by Formula (I-1346)

10.85 Parts of a compound represented by formula (I-1346-d), 13.97 partsof a salt represented by formula (I-1224-e) and 90 parts ofdimethylformamide were mixed, and after stirring at 23° C. for 30minutes, the temperature was raised to 90° C. To the mixture thusobtained, 14.41 parts of potassium carbonate was added, followed bystirring at 90° C. for 3 hours and further cooling to 23° C. To themixture thus obtained, 200 parts of chloroform and 150 parts ofion-exchanged water were added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. To theorganic layer thus obtained, 150 parts of ion-exchanged water was added,and after stirring at 23° C. for 30 minutes, the organic layer wasisolated through separation. This water washing operation was repeatedthree times. The organic layer thus obtained was concentrated, and 10parts of acetonitrile and 210 parts of tert-butyl methyl ether wereadded to the concentrated residue. After stirring at 23° C. for 30minutes, the supernatant was removed, followed by concentration toobtain 24.66 parts of a salt represented by formula (I-1346-f).

0.80 Part of a salt represented by formula (I-1346-f), 0.91 part of asalt represented by formula (I-16-g), 30 parts of chloroform and 15parts of ethyl acetate were mixed, followed by stirring at 23° C. for 2hours. To the mixture thus obtained, 20 parts of ion-exchanged water wasadded, and after stirring at 23° C. for 30 minutes, the organic layerwas isolated through separation. This water washing operation wasrepeated five times. The organic layer thus obtained was concentratedand 30 parts of tert-butyl methyl ether was added to the concentratedresidue, followed by stirring at 23° C. for 30 minutes and furtherfiltration to obtain 1.21 parts of a salt represented by formula(I-1346).

MASS (ESI (+) Spectrum): M⁺ 469.2

MASS (ESI (−) Spectrum): M⁻ 467.1

Example 9: Synthesis of Salt Represented by Formula (I-282)

1.02 Parts of a compound represented by formula (I-1224-d) and 20 partsof tetrahydrofuran were mixed, and after stirring at 23° C. for 30minutes and cooling to 5° C., 0.14 part of sodium hydride was added. Tothe mixture thus obtained, 2.60 parts of a salt represented by formula(I-282-e) was added, followed by stirring at 5° C. for 3 hours. To themixture thus obtained, 6.30 parts of 1N hydrochloric acid was added,followed by temperature rising to 23° C. and further stirring at 23° C.for 6 hours. To the mixture thus obtained, 30 parts of chloroform and 15parts of ion-exchanged water were added, and after stirring at 23° C.for 30 minutes, the organic layer was isolated through separation. Theorganic layer thus obtained was concentrated, and 1 part of acetonitrileand 30 parts of tert-butyl methyl ether were added to the concentratedresidue. After stirring at 23° C. for 30 minutes, the supernatant wasremoved, followed by concentration to obtain 1.95 parts of a saltrepresented by formula (I-282-f).

1.30 Parts of a salt represented by formula (I-282-f) and 30 parts ofdimethylformamide were mixed, and after stirring at 23° C. for 30minutes, 0.16 part of potassium carbonate and 0.05 part of potassiumiodide were added, and then the temperature was raised to 75° C. To themixture thus obtained, 1.13 parts of a compound represented by formula(I-160-a) was added, followed by stirring at 75° C. for 5 hours andfurther cooling to 23° C. To the mixture thus obtained, 50 parts ofchloroform and 20 parts of an aqueous 5% oxalic acid solution wereadded, and after stirring at 23° C. for 30 minutes, the organic layerwas isolated through separation. To the organic layer thus obtained, 20parts of ion-exchanged water was added, and after stirring at 23° C. for30 minutes, the organic layer was isolated through separation. Thiswater washing operation was repeated five times. The organic layer thusobtained was concentrated to obtain 1.53 parts of a compound representedby formula (I-282-g).

1.21 Parts of a salt represented by formula (I-282-g), 0.91 part of asalt represented by formula (I-16-g), 30 parts of chloroform and 15parts of ethyl acetate were mixed, followed by stirring at 23° C. for 2hours. To the mixture thus obtained, 20 parts of ion-exchanged water wasadded, and after stirring at 23° C. for 30 minutes, the organic layerwas isolated through separation. This water washing operation wasrepeated five times. The organic layer thus obtained was concentratedand 30 parts of tert-butyl methyl ether was added to the concentratedresidue, followed by stirring at 23° C. for 30 minutes and furtherfiltration to obtain 1.53 parts of a salt represented by formula(I-282).

MASS (ESI (+) Spectrum): M⁺ 727.2

MASS (ESI (−) Spectrum): M⁻ 467.1

Example 10: Synthesis of Salt Represented by Formula (I-1878)

4.34 Parts of a compound represented by formula (I-1878-b) and 30 partsof dimethylformamide were mixed, followed by stirring at 23° C. for 30minutes. The mixture thus obtained was cooled to 0° C. and then mixedwith 0.30 part of sodium hydride, followed by stirring at 0° C. for 4hours. To the mixture thus obtained, 3.17 parts of a salt represented byformula (I-1224-e) was added at 0° C., followed by stirring at 0° C. for3 hours to obtain a mixture containing a salt represented by formula(I-1878-c). The temperature of the mixture thus obtained was raised to23° C. and 11 parts of an aqueous 5% oxalic acid solution was added, andafter stirring at 23° C. for 30 minutes, 5.70 parts of a saltrepresented by formula (I-16-g) was added, followed by stirring at 23°C. for 7 hours. To the reaction product thus obtained, 60 parts ofchloroform and 30 parts of ion-exchanged water were added, and afterstirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus recovered, 30 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated seven times. The organic layer thusobtained was concentrated and 30 parts of tert-butyl methyl ether wasadded to the concentrated residue. After stirring at 23° C. for 30minutes, the supernatant was removed, followed by concentration toobtain 9.49 parts of a salt represented by formula (I-1878).

MASS (ESI (+) Spectrum): M⁺ 695.0

MASS (ESI (−) Spectrum): M⁻ 467.1

Example 11: Synthesis of Salt Represented by Formula (I-1992)

3.08 Parts of a salt represented by formula (I-1992-b) and 30 parts ofdimethylformamide were mixed, followed by stirring at 23° C. for 30minutes. The mixture thus obtained was cooled to 0° C. and then mixedwith 0.30 part of sodium hydride, followed by stirring at 0° C. for 4hours. To the mixture thus obtained, 3.17 parts of a salt represented byformula (1-1224-e) was added at 0° C., followed by stirring at 0° C. for3 hours to obtain a mixture containing a salt represented by formula(I-1992-c). The temperature of the mixture thus obtained was raised to23° C. and then 11 parts of an aqueous 5% oxalic acid solution wasadded, followed by stirring at 23° C. for 30 minutes, addition of 5.70parts of a salt represented by formula (I-16-g) and further stirring at23° C. for 7 hours. To the reaction product thus obtained, 60 parts ofchloroform and 30 parts of ion-exchanged water were added, and afterstirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus recovered, 30 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated seven times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added to the concentrated residue and, after stirring at 23° C. for30 minutes, the supernatant was removed, followed by concentration toobtain 8.66 parts of a salt represented by formula (I-1992).

MASS (ESI (+) Spectrum): M⁺ 569.1

MASS (ESI (−) Spectrum): M⁻ 467.1

Example 12: Synthesis of Salt Represented by Formula (I-2106)

3.38 Parts of a salt represented by formula (I-2106-b) and 30 parts ofdimethylformamide were mixed, followed by stirring at 23° C. for 30minutes. The mixture thus obtained was cooled to 0° C. and then 0.30part of sodium hydride was added, followed by stirring at 0° C. for 4hours. To the mixture thus obtained, 3.17 parts of a salt represented byformula (I-1224-e) was added at 0° C., followed by stirring at 0° C. for3 hours to obtain a mixture containing a salt represented by formula(I-2106-c). The temperature of the mixture thus obtained was raised to23° C. and then 11 parts of an aqueous 5% oxalic acid solution wasadded, followed by stirring at 23° C. for 30 minutes, addition of 5.70parts of a salt represented by formula (I-16-g) and further stirring at23° C. for 7 hours. To the reaction product thus obtained, 60 parts ofchloroform and 30 parts of ion-exchanged water were added, and afterstirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus recovered, 30 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated seven times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added and, after stirring at 23° C. for 30 minutes, the supernatantwas removed, followed by concentration to obtain 9.13 parts of a saltrepresented by formula (I-2106).

MASS (ESI (+) Spectrum): M⁺ 599.1

MASS (ESI (−) Spectrum): M⁻ 467.1

Example 13: Synthesis of Salt Represented by Formula (I-2220)

4.34 Parts of a compound represented by formula (I-2220-b) and 30 partsof dimethylformamide were mixed, followed by stirring at 23° C. for 30minutes. The mixture thus obtained was cooled to 0° C. and then 0.30part of sodium hydride was mixed, followed by stirring at 0° C. for 4hours. To the mixture thus obtained, 3.17 parts of a salt represented byformula (I-1224-e) was added at 0° C., followed by stirring at 0° C. for3 hours to obtain a mixture containing a salt represented by formula(I-2220-c). The temperature of the mixture thus obtained was raised to23° C. and then 11 parts of an aqueous 5% oxalic acid solution wasadded, followed by stirring at 23° C. for 30 minutes, addition of 5.70parts of a salt represented by formula (I-16-g) and further stirring at23° C. for 7 hours. To the reaction product thus obtained, 60 parts ofchloroform and 30 parts of ion-exchanged water were added, and afterstirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus recovered, 30 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated seven times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added and, after stirring at 23° C. for 30 minutes, the supernatantwas removed, followed by concentration to obtain 7.12 parts of a saltrepresented by formula (I-2220).

MASS (ESI (+) Spectrum): M⁺ 695.0

MASS (ESI (−) Spectrum): M⁻ 467.1

Example 14: Synthesis of Salt Represented by Formula (I-2486)

13.02 Parts of a compound represented by formula (I-1878-b) and 50 partsof dimethylformamide were mixed, followed by stirring at 2300 for 30minutes. The mixture thus obtained was cooled to 000 and then 0.90 partof sodium hydride was mixed, followed by stirring at 000 for 4 hours. Tothe mixture thus obtained, 3.53 parts of a salt represented by formula(I-2486-e) was added at 0°, followed by stirring at 000 for 3 hours toobtain a mixture containing a salt represented by formula (I-2486-c).The temperature of the mixture thus obtained was raised to 23° C. andthen 11 parts of an aqueous 5% oxalic acid solution was added, followedby stirring at 23° C. for 30 minutes, addition of 5.70 parts of a saltrepresented by formula (I-16-g) and further stirring at 23° C. for 7hours. To the reaction product thus obtained, 100 parts of chloroformand 50 parts of ion-exchanged water were added, and after stirring at23° C. for 30 minutes, the organic layer was isolated throughseparation. To the organic layer thus recovered, 30 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated seven times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added and, after stirring at 23° C. for 30 minutes, the supernatantwas removed, followed by concentration to obtain 13.98 parts of a saltrepresented by formula (I-2486).

MASS (ESI (+) Spectrum): M⁺ 1558.7

MASS (ESI (−) Spectrum): M⁻ 467.1

Synthesis Example 1: Synthesis of Salt Represented by Formula (IX-5)

2.25 Parts of a compound represented by formula (IX-5-b) and 30 parts ofchloroform were mixed, followed by stirring at 23° C. for 30 minutes. Tothe mixed solution thus obtained, 0.73 part of carbonyldiimidazole wasadded, followed by stirring at 50° C. for 2 hours. To the mixed solutionthus obtained, 1.42 parts of a salt represented by formula (IX-5-a) wasadded, followed by stirring at 50° C. for 3 hours and further cooling to23° C. To the mixture thus obtained, 15 parts of an aqueous 5% oxalicacid solution was added, and after stirring at 23° C. for 30 minutes,the organic layer was isolated through separation. To the organic layerthus obtained, 15 parts of ion-exchanged water was added, and afterstirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus obtained, 2.63 parts of asalt represented by formula (I-8-g) was added, followed by stirring at23° C. for 2 hours. To the reaction product thus obtained, 30 parts ofchloroform and 30 parts of ion-exchanged water were added, and afterstirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus recovered, 30 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated seven times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwere added to the concentrated residue and, after stirring at 23° C. for30 minutes, the supernatant was removed, followed by concentration toobtain 2.18 parts of a salt represented by formula (IX-5).

MASS (ESI (+) Spectrum): M⁺ 760.8

MASS (ESI (−) Spectrum): M⁻ 517.1

Synthesis Example 2: Synthesis of Salt Represented by Formula (IX-6)

1.43 Parts of a salt represented by formula (I-1224-e), 2.11 parts of acompound represented by formula (IX-6-b) and 10 parts ofdimethylformamide were mixed, followed by stirring at 23° C. for 30minutes. To the mixture thus obtained, 0.40 part of potassium carbonatewas added, followed by stirring at 23° C. for 30 minutes and furtherstirring at 90° C. for 20 hours to obtain a mixture containing a saltrepresented by formula (IX-6-c). The mixture thus obtained was cooled to23° C. and then 11 parts of an aqueous 5% oxalic acid solution wasadded, followed by stirring at 23° C. for 30 minutes, addition of 2.63parts of a salt represented by formula (I-8-g) and further stirring at23° C. for 7 hours. To the reaction product thus obtained, 30 parts ofchloroform and 30 parts of ion-exchanged water were added, and afterstirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus recovered, 30 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated seven times. The organic layer thusobtained was concentrated and then the concentrated mixture was isolatedusing a column (silica gel 60N (spherical, neutral) 100-210 μm;manufactured by Kanto Chemical Co., Inc., developing solvent:methanol/chloroform=1/1) to obtain 0.44 part of a salt represented byformula (IX-6).

MASS (ESI (+) Spectrum): M⁺ 776.8

MASS (ESI (−) Spectrum): M⁻ 517.1

Synthesis of Resin

Compounds (monomers) used in synthesis of a resin (A) are shown below.Hereinafter, these compounds are referred to as “monomer (a1-1-3)”according to the formula number.

Synthesis Example 3 [Synthesis of Resin A1]

Using a monomer (a1-1-3), a monomer (a1-2-6), a monomer (a2-1-3), amonomer (a3-4-2) and a monomer (a1-4-2) as monomers, these monomers weremixed in a molar ratio of 20:35:3:15:27 [monomer (a1-1-3):monomer(a1-2-6):monomer (a2-1-3):monomer (a3-4-2):monomer (a1-4-2)], and thenthis monomer mixture was mixed with methyl isobutyl ketone in the amountof 1.5 mass times the total mass of all monomers. To the mixture thusobtained, azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile)as initiators were added in the amounts of 1.2 mol % and 3.6 mol % basedon the total molar number of all monomers, followed by heating at 73° C.for about 5 hours. Thereafter, to the polymerization reaction solutionthus obtained, an aqueous p-toluenesulfonic acid solution (2.5% byweight) was added in the amount of 2.0 mass times the total mass of allmonomers, followed by stirring for 12 hours and further isolationthrough separation. The organic layer thus recovered was poured into alarge amount of n-heptane to precipitate a resin, followed by filtrationand recovery to obtain a resin A1 having a weight-average molecularweight of about 5.3×10³ in a yield of 63%. This resin A1 has thefollowing structural units.

Synthesis Example 4 [Synthesis of Resin A2]

Using a monomer (a1-1-3), a monomer (a1-2-6), a monomer (a2-1-3), amonomer (a3-4-2) and a monomer (a1-4-13) as monomers, these monomerswere mixed in a molar ratio of 20:35:3:15:27 [monomer (a1-1-3):monomer(a1-2-6):monomer (a2-1-3):monomer (a3-4-2):monomer (a1-4-13)], and thenthis monomer mixture was mixed with methyl isobutyl ketone in the amountof 1.5 mass times the total mass of all monomers. To the mixture thusobtained, azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile)as initiators were added in the amounts of 1.2 mol % and 3.6 mol % basedon the total molar number of all monomers, followed by heating at 73° C.for about 5 hours. Thereafter, to the polymerization reaction solutionthus obtained, an aqueous p-toluenesulfonic acid solution (2.5% byweight) was added in the amount of 2.0 mass times the total mass of allmonomers, followed by stirring for 12 hours and further isolationthrough separation. The organic layer thus recovered was poured into alarge amount of n-heptane to precipitate a resin, followed by filtrationand recovery to obtain a resin A2 having a weight-average molecularweight of about 5.1×10³ in a yield of 61%. This resin A2 has thefollowing structural units.

Synthesis Example 5 [Synthesis of Resin A3]

Using a monomer (a1-2-6), a monomer (a2-1-3), a monomer (a3-4-2) and amonomer (a1-4-19) as monomers, these monomers were mixed in a molarratio of 53:3:12:32 [monomer (a1-2-6):monomer (a2-1-3):monomer(a3-4-2):monomer (a1-4-19)], and then this monomer mixture was mixedwith methyl isobutyl ketone in the amount of 1.5 mass times the totalmass of all monomers. To the mixture thus obtained,azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile) asinitiators were added in the amounts of 1.2 mol % and 3.6 mol % based onthe total molar number of all monomers, followed by heating at 73° C.for about 5 hours. Thereafter, to the polymerization reaction solutionthus obtained, an aqueous p-toluenesulfonic acid solution (2.5% byweight) was added in the amount of 2.0 mass times the total mass of allmonomers, followed by stirring for 12 hours and further isolationthrough separation. The organic layer thus recovered was poured into alarge amount of n-heptane to precipitate a resin, followed by filtrationand recovery to obtain a resin A3 having a weight-average molecularweight of about 5.5×10³ in a yield of 74%. This resin A3 has thefollowing structural units.

Synthesis Example 6 [Synthesis of Resin A4]

Using a monomer (a1-2-6), a monomer (a2-1-3), a monomer (a3-4-2) and amonomer (a1-4-2) as monomers, these monomers were mixed in a molar ratioof 53:3:12:32 [monomer (a1-2-6):monomer (a2-1-3):monomer(a3-4-2):monomer (a1-4-2)], and then this monomer mixture was mixed withmethyl isobutyl ketone in the amount of 1.5 mass times the total mass ofall monomers. To the mixture thus obtained, azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) as initiators were added in theamounts of 1.2 mol % and 3.6 mol % based on the total molar number ofall monomers, followed by heating at 73° C. for about 5 hours.Thereafter, to the polymerization reaction solution thus obtained, anaqueous p-toluenesulfonic acid solution (2.5% by weight) was added inthe amount of 2.0 mass times the total mass of all monomers, followed bystirring for 12 hours and further isolation through separation. Theorganic layer thus recovered was poured into a large amount of n-heptaneto precipitate a resin, followed by filtration and recovery to obtain aresin A4 having a weight-average molecular weight of about 5.3×10³ in ayield of 88%. This resin A4 has the following structural units.

Synthesis Example 7 [Synthesis of Resin A5]

Using a monomer (a1-2-6), a monomer (a2-1-3), a monomer (a3-4-2) and amonomer (a1-4-13) as monomers, these monomers were mixed in a molarratio of 53:3:12:32 [monomer (a1-2-6):monomer (a2-1-3):monomer(a3-4-2):monomer (a1-4-13)], and then this monomer mixture was mixedwith methyl isobutyl ketone in the amount of 1.5 mass times the totalmass of all monomers. To the mixture thus obtained,azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile) asinitiators were added in the amounts of 1.2 mol % and 3.6 mol % based onthe total molar number of all monomers, followed by heating at 73° C.for about 5 hours. Thereafter, to the polymerization reaction solutionthus obtained, an aqueous p-toluenesulfonic acid solution (2.5% byweight) was added in the amount of 2.0 mass times the total mass of allmonomers, followed by stirring for 12 hours and further isolationthrough separation. The organic layer thus obtained was poured into alarge amount of n-heptane to precipitate a resin, followed by filtrationand recovery to obtain a resin A5 having a weight-average molecularweight of about 5.1×10³ in a yield of 79%. This resin A5 has thefollowing structural units.

<Preparation of Resist Composition>

As shown in Table 2, the following components were mixed and the mixturethus obtained was filtered through a fluororesin filter having a porediameter of 0.2 μm to prepare resist compositions.

TABLE 2 Resist Acid Salt Quencher PB/ composition Resin generator (I)(C) PEB Composition A2 = — I-160 = C1 = 100° C./ 1 10 parts 1.5 parts0.35 part 130° C. Composition A1 = — I-160 = C1 = 100° C./ 2 10 parts1.5 parts 0.35 part 130° C. Composition A1 = — I-168 = C1 = 100° C./ 310 parts 1.5 parts 0.35 part 130° C. Composition A1 = — I-156 = C1 =100° C./ 4 10 parts 1.5 parts 0.35 part 130° C. Composition A1 = —I-1224 = C1 = 100° C./ 5 10 parts 1.5 parts 0.35 part 130° C.Composition A1 = — I-1232 = C1 = 100° C./ 6 10 parts 1.5 parts 0.35 part130° C. Composition A1 = — I-8 = C1 = 100° C./ 7 10 parts 1.5 parts 0.35part 130° C. Composition A1 = — I-16 = C1 = 100° C./ 8 10 parts 1.5parts 0.35 part 130° C. Composition A1 = — I-1346 = C1 = 100° C./ 9 10parts 1.5 parts 0.35 part 130° C. Composition A1 = — I-282 = C1 = 100°C./ 10 10 parts 1.5 parts 0.35 part 130° C. Composition A1 = — I-1878 =C1 = 100° C./ 11 10 parts 1.5 parts 0.35 part 130° C. Composition A1 = —I-1992 = C1 = 100° C./ 12 10 parts 1.5 parts 0.35 part 130° C.Composition A1 = — I-2106 = C1 = 100° C./ 13 10 parts 1.5 parts 0.35part 130° C. Composition A1 = — I-2220 = C1 = 100° C./ 14 10 parts 1.5parts 0.35 part 130° C. Composition A2 = — I-1878 = C1 = 100° C./ 15 10parts 1.5 parts 0.35 part 130° C. Composition A3 = — I-1878 = C1 = 100°C./ 16 10 parts 1.5 parts 0.35 part 130° C. Composition A4 = — I-1878 =C1 = 100° C./ 17 10 parts 1.5 parts 0.35 part 130° C. Composition A5 = —I-1878 = C1 = 100° C./ 18 10 parts 1.5 parts 0.35 part 130° C.Composition A1 = — I-2486 = C1 = 100° C./ 19 10 parts 1.5 parts 0.35part 130° C. Comparative A1 = IX-1 = — C1 = 100° C./ Composition 10parts 1.5 parts 0.35 part 130° C. 1 Comparative A1 = IX-2 = — C1 = 100°C./ Composition 10 parts 1.5 parts 0.35 part 130° C. 2 Comparative A1 =IX-3 = — C1 = 100° C./ Composition 10 parts 1.5 parts 0.35 part 130° C.3 Comparative A1 = IX-4 = — C1 = 100° C./ Composition 10 parts 1.5 parts0.35 part 130° C. 4 Comparative A1 = IX-5 = — C1 = 100° C./ Composition10 parts 1.5 parts 0.35 part 130° C. 5 Comparative A1 = IX-6 = — C1 =100° C./ Composition 10 parts 1.5 parts 0.35 part 130° C. 6<Resin>

-   -   A1 to A5: Resin A1 to Resin A5        <Salt (I)>    -   I-8: salt represented by formula (I-8)    -   I-16: salt represented by formula (I-16)    -   I-156: salt represented by formula (I-156)    -   I-160: salt represented by formula (I-160)    -   I-168: Salt represented by formula (I-168)    -   I-282: Salt represented by formula (I-282)    -   I-1224: Salt represented by formula (I-1224)    -   I-1232: Salt represented by formula (I-1232)    -   I-1346: Salt represented by formula (I-1346)    -   I-1878: Salt represented by formula (I-1878)    -   I-1992: Salt represented by formula (I-1992)    -   I-2106: Salt represented by formula (I-2106)    -   I-2220: Salt represented by formula (I-2220)    -   I-2486: Salt represented by formula (I-2486)        <Acid Generator>    -   IX-1    -   IX-2    -   IX-3    -   IX-4

-   -   IX-5: Salt represented by formula (IX-5)    -   IX-6: Salt represented by formula (IX-6)        <Quencher (C)>    -   C1: synthesized by the method mentioned in JP 2011-39502 A

<Solvent>

Propylene glycol monomethyl ether acetate 400 parts Propylene glycolmonomethyl ether 100 parts γ-Butyrolactone  5 parts(Evaluation of Exposure of Resist Composition with Electron Beam,Organic Solvent Development)

Each 6 inch-diameter silicon wafer was treated with hexamethyldisilazaneon a direct hot plate at 90° C. for 60 seconds. A resist composition wasspin-coated on the silicon wafer in such a manner that the thickness ofthe composition layer became 0.04 μm. Then, the coated silicon wafer wasprebaked on the direct hot plate at the temperature shown in the column“PB” of Table 2 for 60 seconds to form a composition layer. Using anelectron-beam direct-write system (“ELS-F125 125 keV”, manufactured byELIONIX INC.), contact hole patterns (hole pitch of 40 nm/hole diameterof 17 nm) were directly written on the composition layer formed on thewafer while changing the exposure dose stepwise.

After exposure, post-exposure baking was performed on the hot plate atthe temperature shown in the column “PEB” of Table 2 for 60 seconds.Next, the composition layer on this silicon wafer was developed withbutyl acetate (manufactured by Tokyo Chemical Industry Co., Ltd.) as adeveloper at 23° C. for 20 seconds using the dynamic dispensing methodto obtain resist patterns.

In the resist pattern obtained after development, the exposure dose atwhich the diameter of holes formed became 17 nm was regarded aseffective sensitivity.

<Evaluation of CD Uniformity (CDU)>

In the effective sensitivity, the hole diameter of the pattern formedwith a hole dimeter of 17 nm was determined by measuring 24 times perone hole and the average of the measured values was regarded as theaverage hole diameter. The standard deviation was determined under theconditions that the average diameter of 400 holes about the patternsformed with a hole dimeter of 17 nm in the same wafer was regarded to aspopulation.

The results are shown in Table 3. The numerical value in the tablerepresents the standard deviation (nm).

TABLE 3 Resist composition CDU Example 15 Composition 1 2.51 Example 16Composition 2 2.58 Example 17 Composition 3 2.52 Example 18 Composition4 2.69 Example 19 Composition 5 2.62 Example 20 Composition 6 2.55Example 21 Composition 7 2.68 Example 22 Composition 8 2.62 Example 23Composition 9 2.53 Example 24 Composition 10 2.42 Example 25 Composition11 2.33 Example 26 Composition 12 2.38 Example 27 Composition 13 2.32Example 28 Composition 14 2.35 Example 29 Composition 15 2.24 Example 30Composition 16 2.28 Example 31 Composition 17 2.35 Example 32Composition 18 2.26 Example 33 Composition 19 2.24 Comparative Example 1Comparative Composition 1 2.89 Comparative Example 2 ComparativeComposition 2 2.92 Comparative Example 3 Comparative Composition 3 2.99Comparative Example 4 Comparative Composition 4 2.88 Comparative Example5 Comparative Composition 5 2.89 Comparative Example 6 ComparativeComposition 6 2.83

As compared with Comparative Compositions 1 to 6, Compositions 1 to 19exhibited satisfactory evaluation of CD uniformity (CDU).

A resist composition including a salt of the present invention iscapable of obtaining a resist pattern with satisfactory CD uniformity(CDU), and is therefore useful for fine processing of semiconductors andis industrially extremely useful.

What is claimed is:
 1. A salt represented by formula (I):

wherein, in formula (I), R¹, R² and R³ each independently represent ahydroxy group, *—O—R¹⁰, * —O—CO—O—R¹⁰ or *—O-L¹⁰-CO—O—R¹⁰, and *represents a bonding site to the benzene ring, L¹⁰ represents analkanediyl group having 1 to 6 carbon atoms, R¹⁰ represents anacid-labile group, R⁴, R⁵, R⁶, R⁷, R⁸ and R⁹ each independentlyrepresent a halogen atom, a haloalkyl group having 1 to 12 carbon atomsor a hydrocarbon group having 1 to 18 carbon atoms, the hydrocarbongroup may have a substituent, and —CH₂— included in the haloalkyl groupand the hydrocarbon group may be replaced by —O—, —S—, —CO— or —SO₂—,A¹, A² and A³ each independently represent a hydrocarbon group having 2to 20 carbon atoms, the hydrocarbon group may have a substituent, and—CH₂— included in the hydrocarbon group may be replaced by —O—, —CO—,—S— or —SO₂—, m1 represents an integer of 1 to 5, and when m1 is 2 ormore, a plurality of groups in parentheses may be the same or differentfrom each other, m2 represents an integer of 0 to 5, and when m2 is 2 ormore, a plurality of groups in parentheses may be the same or differentfrom each other, m3 represents an integer of 0 to 5, and when m3 is 2 ormore, a plurality of groups in parentheses may be the same or differentfrom each other, m4 represents an integer of 0 to 4, and when m4 is 2 ormore, a plurality of R⁴ may be the same or different from each other, m5represents an integer of 0 to 4, and when m5 is 2 or more, a pluralityof R⁵ may be the same or different from each other, m6 represents aninteger of 0 to 4, and when m6 is 2 or more, a plurality of R⁶ may bethe same or different from each other, m7 represents an integer of 0 to4, and when m7 is 2 or more, a plurality of R⁷ may be the same ordifferent from each other, m8 represents an integer of 0 to 5, and whenm8 is 2 or more, a plurality of R⁸ may be the same or different fromeach other, m9 represents an integer of 0 to 5, and when m9 is 2 ormore, a plurality of R⁹ may be the same or different from each other, inwhich 1≤m1+m7≤5, 0≤m2+m8≤5, 0≤m3+m9≤5, and AI⁻ represents a sulfonicacid anion, a sulfonylimide anion, a sulfonylmethide anion or acarboxylic acid anion, provided that the sulfonic acid anion does notcomprise a structure represented by —C(H)(F)—C(F)(F)—SO₃ ⁻.
 2. The saltaccording to claim 1, wherein A¹ is *—X⁰¹-L⁰¹- or *-L⁰¹-X⁰¹—, A² is*—X⁰²-L⁰²- or *-L⁰²-X⁰²— and A³ is *—X⁰³-L⁰³- or *-L⁰³-X⁰³—, whereinX⁰¹, X⁰² and X⁰³ each independently represent —O—, —CO—, —S— or —SO₂—,L⁰¹, L⁰² and L⁰³ each independently represent a hydrocarbon group having1 to 19 carbon atoms, the hydrocarbon group may have a substituent,—CH₂— included in the hydrocarbon group may be replaced by —O—, —CO—,—S— or —SO₂—, and * represents a bonding site to the benzene ring towhich R¹, R² or R³ is bonded.
 3. The salt according to claim 2, whereinX⁰¹, X⁰² and X⁰³ are each independently —O— or —S—.
 4. The saltaccording to claim 2, wherein L⁰¹, L⁰² and L⁰³ are each independently analkanediyl group having 1 to 6 carbon atoms and —CH₂— included in thealkanediyl group may be replaced by —O— or —CO—.
 5. The salt accordingto claim 1, wherein R¹, R² and R³ are each independently a hydroxygroup, *—O—R¹⁰ or *—O-L¹⁰-CO—O—R¹⁰ and * represents a bonding site tothe benzene ring.
 6. The salt according to claim 1, wherein theacid-labile group as for R¹⁰ is a group represented by formula (1a) or agroup represented by formula (2a):

wherein, in formula (1a), Raa1, R^(aa1), R^(aa2) and R^(aa3) eachindependently represent an alkyl group having 1 to 8 carbon atoms, analkenyl group having 2 to 8 carbon atoms, an alicyclic hydrocarbon grouphaving 3 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to18 carbon atoms, or a group obtained by combining these groups, orR^(aa1) and R^(aa2) may be bonded to each other to form an alicyclichydrocarbon group having 3 to 20 carbon atoms together with carbon atomsto which R^(aa1) and R^(aa2) are bonded, and * represents a bondingsite:

wherein, in formula (2a), R^(aa1′) and R^(aa2′) each independentlyrepresent a hydrogen atom or a hydrocarbon group having 1 to 12 carbonatoms, R^(aa3′) represents a hydrocarbon group having 1 to 20 carbonatoms, or R^(aa2′) and R^(aa3′) may be bonded to each other to form aheterocyclic group having 3 to 20 carbon atoms together with —C—X^(a)—to which R^(aa2′) and R^(aa3′) are bonded, and —CH₂— included in thehydrocarbon group and the heterocyclic group may be replaced by —O— or—S—, X^(a) represents an oxygen atom or a sulfur atom, and * representsa bonding site.
 7. The salt according to claim 1, wherein when m4, m5 orm6 is an integer of 1 or more, R⁴, R⁵ and R⁶ are each independently afluorine atom, an iodine atom, a perfluoroalkyl group having 1 to 4carbon atoms or an alkyl group having 1 to 4 carbon atoms and —CH₂—included in the alkyl group may be replaced by —O— or —CO—.
 8. The saltaccording to claim 1, wherein when m7, m8 or m9 is an integer of 1 ormore, R⁷, R⁸ and R⁹ are each independently a fluorine atom, an iodineatom, a perfluoroalkyl group having 1 to 4 carbon atoms or an alkylgroup having 1 to 4 carbon atoms and —CH₂— included in the alkyl groupmay be replaced by —O— or —CO—.
 9. The salt according to claim 1,wherein AI⁻ is a sulfonic acid anion, and the sulfonic acid anion is ananion represented by formula (I-A):

wherein, in formula (I-A), Q¹ and Q² each independently represent ahydrogen atom, a fluorine atom, an alkyl group having 1 to 6 carbonatoms or a perfluoroalkyl group having 1 to 6 carbon atoms, L¹represents a saturated hydrocarbon group having 1 to 24 carbon atoms,—CH₂— included in the saturated hydrocarbon group may be replaced by —O—or —CO—, and a hydrogen atom included in the saturated hydrocarbon groupmay be substituted with a fluorine atom or a hydroxy group, providedthat when Q¹ and Q² are fluorine atoms, the group directly attached to—C(Q¹)(Q²)- is not —C(H)(F)—, and Y¹ represents a methyl group which mayhave a substituent, or an alicyclic hydrocarbon group having 3 to 24carbon atoms which may have a substituent, and —CH₂— included in thealicyclic hydrocarbon group may be replaced by —O—, —S—, —SO₂— or —CO—.10. An acid generator comprising the salt according to claim
 1. 11. Aresist composition comprising the acid generator according to claim 10and a resin having an acid-labile group.
 12. The resist compositionaccording to claim 11, wherein the resin having an acid-labile groupincludes at least one selected from the group consisting of a structuralunit represented by formula (a1-0), a structural unit represented byformula (a1-1) and a structural unit represented by formula (a1-2):

wherein, in formula (a1-0), formula (a1-1) and formula (a1-2), L^(a01),L^(a1) and L^(a2) each independently represent —O— or*—O—(CH₂)_(k1)—CO—O—, k1 represents an integer of 1 to 7, and *represents a bonding site to —CO—, R^(a01), R^(a4) and R^(a5) eachindependently represent a hydrogen atom, a halogen atom, or an alkylgroup having 1 to 6 carbon atoms which may have a halogen atom, R^(a02),R^(a03) and R^(a04) each independently represent an alkyl group having 1to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbonatoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or agroup obtained by combining these groups, R^(a6) and R^(a7) eachindependently represent an alkyl group having 1 to 8 carbon atoms, analkenyl group having 2 to 8 carbon atoms, an alicyclic hydrocarbon grouphaving 3 to 18 carbon atoms, an aromatic hydrocarbon group having 6 to18 carbon atoms, or a group formed by combining these groups, m1represents an integer of 0 to 14, n1 represents an integer of 0 to 10,and n1′ represents an integer of 0 to
 3. 13. The resist compositionaccording to claim 11, wherein the resin having an acid-labile groupincludes a structural unit represented by formula (a2-A) or a structuralunit represented by formula (a2-1):

wherein, in formula (a2-A), R^(a50) represents a hydrogen atom, ahalogen atom, or an alkyl group having 1 to 6 carbon atoms which mayhave a halogen atom, R^(a51) represents a halogen atom, a hydroxy group,an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, analkoxyalkoxy group having 2 to 12 carbon atoms, an alkylcarbonyl grouphaving 2 to 4 carbon atoms, an alkylcarbonyloxy group having 2 to 4carbon atoms, an acryloyloxy group or a methacryloyloxy group, A^(a50)represents a single bond or *—X^(a5)-(A^(a52)-X^(a52))_(nb)—, and *represents a bonding site to carbon atoms to which —R^(a50) is bonded,A^(a52) represents an alkanediyl group having 1 to 6 carbon atoms,X^(a51) and X^(a52) each independently represent —O—, —CO—O— or —O—CO—,nb represents 0 or 1, and mb represents an integer of 0 to 4, and whenmb is an integer of 2 or more, a plurality of R^(a51) may be the same ordifferent from each other,

wherein, in formula (a2-1), L^(a3) represents —O— or*—O—(CH₂)_(k2)—CO—O—, k2 represents an integer of 1 to 7, and *represents a bonding site to —CO—, R^(a14) represents a hydrogen atom ora methyl group, R^(a15) and R^(a16) each independently represent ahydrogen atom, a methyl group or a hydroxy group, and o1 represents aninteger of 0 to
 10. 14. The resist composition according to claim 11,further comprising a salt generating an acid having an acidity lowerthan that of an acid generated from the acid generator.
 15. A method forproducing a resist pattern, which comprises: (1) a step of applying theresist composition according to claim 11 on a substrate, (2) a step ofdrying the applied resist composition to form a composition layer, (3) astep of exposing the composition layer, (4) a step of heating theexposed composition layer, and (5) a step of developing the heatedcomposition layer.
 16. The salt according to claim 9, wherein when Q¹and Q² are fluorine atoms, a hydrogen atom included in —CH₂— in thesaturated hydrocarbon group directly attached to —CQ¹Q²-is notsubstituted with a fluorine atom.
 17. The salt according to claim 6,wherein when R¹ is *—O-L¹⁰-CO—O—R¹⁰ and R¹⁰ is a group represented byformula (1a), m4 is an integer of 1 to
 4. 18. The acid generatoraccording to claim 10, which is not a salt comprising a sulfonic acidanion comprising a structure represented by —C(H)(F)—C(F)(F)—SO₃ ⁻.